1 00:00:00,040 --> 00:00:02,460 The following content is provided under a Creative 2 00:00:02,460 --> 00:00:03,970 Commons license. 3 00:00:03,970 --> 00:00:06,910 Your support will help MIT OpenCourseWare continue to 4 00:00:06,910 --> 00:00:10,660 offer high-quality educational resources for free. 5 00:00:10,660 --> 00:00:13,460 To make a donation or view additional materials from 6 00:00:13,460 --> 00:00:17,390 hundreds of MIT courses, visit MIT OpenCourseWare at 7 00:00:17,390 --> 00:00:18,640 ocw.mit.edu. 8 00:00:21,690 --> 00:00:23,835 PROFESSOR: OK, interactive teaching. 9 00:00:35,120 --> 00:00:39,500 Here is a famous graph produced by Benjamin bloom and 10 00:00:39,500 --> 00:00:40,560 his students. 11 00:00:40,560 --> 00:00:42,910 So here on this axis is student achievement. 12 00:00:51,990 --> 00:00:54,550 So after a course is over, students are 13 00:00:54,550 --> 00:00:56,070 tested on the material. 14 00:00:56,070 --> 00:00:57,700 And here's their score. 15 00:00:57,700 --> 00:01:01,020 And this is the percentage who attained each score. 16 00:01:01,020 --> 00:01:05,610 So here, they compared three methods of teaching, but I'll 17 00:01:05,610 --> 00:01:07,660 just compare two. 18 00:01:07,660 --> 00:01:12,460 So one method is standard one-group instruction, say 19 00:01:12,460 --> 00:01:15,440 one-to-30, or today, maybe one-to-90. 20 00:01:21,672 --> 00:01:25,180 And here is the histogram, the distribution of students' 21 00:01:25,180 --> 00:01:28,400 scores, nicely spread out. 22 00:01:28,400 --> 00:01:30,050 Now, by itself, it doesn't say much. 23 00:01:30,050 --> 00:01:34,890 But what's really interesting is the distribution base after 24 00:01:34,890 --> 00:01:38,510 the same amount of teaching, but done in a tutorial form, 25 00:01:38,510 --> 00:01:40,260 with one-to-one or maybe one-to-two. 26 00:01:48,244 --> 00:01:51,340 You can put some quantitative figures on this 27 00:01:51,340 --> 00:01:53,690 from Bloom's results. 28 00:01:53,690 --> 00:01:54,830 The average-- 29 00:01:54,830 --> 00:02:06,810 so this is one-to-one tutoring, one-to-30. 30 00:02:06,810 --> 00:02:13,830 The average tutorial student is two sigmas better than the 31 00:02:13,830 --> 00:02:15,020 group students. 32 00:02:15,020 --> 00:02:17,830 In other words, the average tutorial student is at the 33 00:02:17,830 --> 00:02:22,840 98th percentile of the ordinary teaching group. 34 00:02:22,840 --> 00:02:26,610 So the question is-- 35 00:02:26,610 --> 00:02:31,870 the natural question is, how can we make group instruction 36 00:02:31,870 --> 00:02:35,260 as effective as tutorial instruction? 37 00:02:35,260 --> 00:02:40,310 As Benjamin Bloom says, he says, finding such methods 38 00:02:40,310 --> 00:02:42,680 would be an educational contribution of 39 00:02:42,680 --> 00:02:44,190 the greatest magnitude. 40 00:02:44,190 --> 00:02:46,230 Because, for example, it would change our 41 00:02:46,230 --> 00:02:48,340 notions about human potential. 42 00:02:48,340 --> 00:02:51,540 We'd actually realize, oh, actually, there's not that 43 00:02:51,540 --> 00:02:54,530 much innate in what people can do. 44 00:02:54,530 --> 00:02:57,080 Most of it is how well they've learned, how well 45 00:02:57,080 --> 00:02:58,750 they've been taught. 46 00:02:58,750 --> 00:03:01,590 So the great question-- 47 00:03:01,590 --> 00:03:04,170 and it's the title of Bloom's paper-- is the search for 48 00:03:04,170 --> 00:03:06,980 methods of group instruction as effective 49 00:03:06,980 --> 00:03:09,540 as one-to-one tutoring. 50 00:03:09,540 --> 00:03:13,320 To that end, let's think about the following question, which 51 00:03:13,320 --> 00:03:17,220 is, what makes tutoring so effective? 52 00:03:17,220 --> 00:03:20,460 So I'm going to ask you that, to consider that question in 53 00:03:20,460 --> 00:03:24,140 groups of two and three, whatever's sort of convenient 54 00:03:24,140 --> 00:03:25,960 in your region of the room. 55 00:03:25,960 --> 00:03:28,990 So, what makes tutoring so effective? 56 00:03:28,990 --> 00:03:32,320 After you discuss, we'll take reasons, put them on the 57 00:03:32,320 --> 00:03:36,700 board, and then I'll show you methods of group instruction 58 00:03:36,700 --> 00:03:39,770 that may not quite get us all the way to tutoring, but that 59 00:03:39,770 --> 00:03:42,790 answer many of the good characteristics of tutoring 60 00:03:42,790 --> 00:03:45,940 and bring them into group instruction. 61 00:03:45,940 --> 00:03:48,910 OK, so please find one or two neighbors. 62 00:03:48,910 --> 00:03:50,980 Introduce yourselves. 63 00:03:50,980 --> 00:03:51,540 You never know. 64 00:03:51,540 --> 00:03:54,400 You might find a teaching colleague. 65 00:03:54,400 --> 00:03:58,450 And think about what makes tutoring so effective. 66 00:03:58,450 --> 00:04:02,670 OK, so take 30 seconds and collect 67 00:04:02,670 --> 00:04:03,920 your thoughts together. 68 00:04:09,160 --> 00:04:12,020 OK, who would like to suggest something that your group 69 00:04:12,020 --> 00:04:12,360 thought of? 70 00:04:12,360 --> 00:04:14,720 You don't necessarily have to believe it, just something you 71 00:04:14,720 --> 00:04:17,740 discussed and think we should share. 72 00:04:22,120 --> 00:04:22,570 Yes? 73 00:04:22,570 --> 00:04:23,430 Could you tell me your name? 74 00:04:23,430 --> 00:04:24,140 AUDIENCE: Elena. 75 00:04:24,140 --> 00:04:24,485 PROFESSOR: Elena. 76 00:04:24,485 --> 00:04:26,990 AUDIENCE: For one-on-one tutoring, I imagine there's 77 00:04:26,990 --> 00:04:31,554 less time for misconceptions to get 78 00:04:31,554 --> 00:04:33,030 ingrained in your brain. 79 00:04:33,030 --> 00:04:35,100 PROFESSOR: OK, you can nip misconceptions in the bud. 80 00:04:46,180 --> 00:04:48,820 Whereas in, for example, group instruction, you may not even 81 00:04:48,820 --> 00:04:50,750 know the students have a misconception 82 00:04:50,750 --> 00:04:53,090 until the final exam. 83 00:04:53,090 --> 00:04:55,510 Then what do you do? 84 00:04:55,510 --> 00:04:57,320 OK, let's see. 85 00:04:57,320 --> 00:04:58,766 This group, could you tell me your name? 86 00:04:58,766 --> 00:04:59,580 AUDIENCE: So we thought-- 87 00:04:59,580 --> 00:05:00,840 PROFESSOR: Could you tell me your name? 88 00:05:00,840 --> 00:05:01,302 AUDIENCE: Eric. 89 00:05:01,302 --> 00:05:02,688 PROFESSOR: Eric. 90 00:05:02,688 --> 00:05:05,030 AUDIENCE: We thought in a group, there's probably a lot 91 00:05:05,030 --> 00:05:08,774 of just dissemination of information. 92 00:05:08,774 --> 00:05:11,259 And in one-on-one tutoring, it's probably not one person 93 00:05:11,259 --> 00:05:13,605 just telling person two a bunch of stuff. 94 00:05:13,605 --> 00:05:16,440 It's going through exam problems. 95 00:05:16,440 --> 00:05:17,010 PROFESSOR: Right, OK. 96 00:05:17,010 --> 00:05:20,640 So the contrast in this is what does the teaching 97 00:05:20,640 --> 00:05:21,520 situation look like? 98 00:05:21,520 --> 00:05:25,430 In a typical lecture, someone may just talk at you for 50 99 00:05:25,430 --> 00:05:28,970 minutes, whereas it's hard to imagine a one-on-one tutorial 100 00:05:28,970 --> 00:05:31,960 situation where you walk in for your tutorial, and they 101 00:05:31,960 --> 00:05:33,820 just talk at you for 50 minutes. 102 00:05:33,820 --> 00:05:37,400 That would seem so odd and so counter to all conventions of 103 00:05:37,400 --> 00:05:38,650 human discussion. 104 00:05:40,520 --> 00:05:42,800 It would take a really, really disciplined and well-trained 105 00:05:42,800 --> 00:05:44,840 person to sit still for 50 minutes for that kind of 106 00:05:44,840 --> 00:05:49,880 treatment, so not initially a good kind of training either. 107 00:05:49,880 --> 00:05:55,140 OK, so I'll say you cannot yammer at the audience for 50 108 00:05:55,140 --> 00:05:56,390 minutes straight. 109 00:06:08,600 --> 00:06:09,830 Yes, can you tell me your name? 110 00:06:09,830 --> 00:06:10,370 AUDIENCE: Sorry? 111 00:06:10,370 --> 00:06:11,570 PROFESSOR: Could you tell me your name? 112 00:06:11,570 --> 00:06:12,120 AUDIENCE: I'm Whitney. 113 00:06:12,120 --> 00:06:12,660 PROFESSOR: Whitney 114 00:06:12,660 --> 00:06:16,580 AUDIENCE: I think it follows from this discussion that 115 00:06:16,580 --> 00:06:24,420 arises between two people that the student experiences 116 00:06:24,420 --> 00:06:27,360 validation of what they've understood, and it helps build 117 00:06:27,360 --> 00:06:28,360 their confidence. 118 00:06:28,360 --> 00:06:30,830 PROFESSOR: OK, because they're talking in a small group, so 119 00:06:30,830 --> 00:06:33,050 they can get validation in a safe setting. 120 00:06:33,050 --> 00:06:34,640 Is that? 121 00:06:34,640 --> 00:06:37,440 OK, so it's safe. 122 00:06:41,550 --> 00:06:43,890 It's a safe setting for raising ideas maybe that 123 00:06:43,890 --> 00:06:45,140 you're not sure about. 124 00:06:54,160 --> 00:06:55,280 OK, there was one more. 125 00:06:55,280 --> 00:06:56,330 Yeah, can you tell me your name? 126 00:06:56,330 --> 00:06:56,870 AUDIENCE: Martin. 127 00:06:56,870 --> 00:06:57,670 PROFESSOR: Martin. 128 00:06:57,670 --> 00:06:58,315 AUDIENCE: Yeah. 129 00:06:58,315 --> 00:07:01,030 With tutoring, it's much easier to identify exactly 130 00:07:01,030 --> 00:07:04,930 what the student has trouble understanding, and then tailor 131 00:07:04,930 --> 00:07:07,026 the teaching according to that. 132 00:07:07,026 --> 00:07:09,810 PROFESSOR: OK, so you can tailor the teaching according 133 00:07:09,810 --> 00:07:11,230 to what you find out. 134 00:07:11,230 --> 00:07:15,920 So sort of like the new electronic SATs. 135 00:07:15,920 --> 00:07:18,410 According to what you don't know or do know, in each 136 00:07:18,410 --> 00:07:20,930 question, they give you questions based on your 137 00:07:20,930 --> 00:07:23,600 previous answers at the right level of difficulty. 138 00:07:23,600 --> 00:07:24,850 So you can tailor. 139 00:07:36,360 --> 00:07:37,550 Yeah, can you tell me your name? 140 00:07:37,550 --> 00:07:37,890 AUDIENCE: Azrael. 141 00:07:37,890 --> 00:07:39,462 PROFESSOR: Azrael, yeah. 142 00:07:39,462 --> 00:07:42,360 AUDIENCE: I think related to this, it's very valuable to be 143 00:07:42,360 --> 00:07:44,676 able to tailor your teaching style to the student 144 00:07:44,676 --> 00:07:45,926 [INAUDIBLE] 145 00:07:48,008 --> 00:07:51,350 in general, not just specific points [INAUDIBLE]. 146 00:07:51,350 --> 00:07:52,670 PROFESSOR: OK, you can tailor the teaching 147 00:07:52,670 --> 00:07:53,740 style to the student. 148 00:07:53,740 --> 00:07:56,460 If, for example, the student is-- 149 00:07:56,460 --> 00:07:58,790 for example, suppose you're teaching math to somebody 150 00:07:58,790 --> 00:08:00,280 who's an architect. 151 00:08:00,280 --> 00:08:02,670 Well, you can use lots of examples that are particular 152 00:08:02,670 --> 00:08:04,940 to something they're totally fascinated by. 153 00:08:04,940 --> 00:08:06,745 You can tailor a teaching method. 154 00:08:10,390 --> 00:08:14,440 OK, let me get something from somewhere back there, in case 155 00:08:14,440 --> 00:08:16,140 I've been neglecting people way in the back. 156 00:08:19,044 --> 00:08:21,820 Oh, go ahead. 157 00:08:21,820 --> 00:08:22,655 You guys had your chance. 158 00:08:22,655 --> 00:08:24,290 I'll be back. 159 00:08:24,290 --> 00:08:26,170 Can you tell me your name? 160 00:08:26,170 --> 00:08:27,190 AUDIENCE: Graham. 161 00:08:27,190 --> 00:08:28,940 PROFESSOR: Graham. 162 00:08:28,940 --> 00:08:31,730 AUDIENCE: Just the level of engagement, it is impossible 163 00:08:31,730 --> 00:08:37,640 to sit there in a one-on-one setting and think about the 164 00:08:37,640 --> 00:08:39,919 music you like [INAUDIBLE] 165 00:08:39,919 --> 00:08:42,600 the subject matter at hand. 166 00:08:42,600 --> 00:08:43,030 PROFESSOR: Right. 167 00:08:43,030 --> 00:08:47,200 OK, so the level of engagement is much higher in a tutorial. 168 00:08:47,200 --> 00:08:50,440 So that's the complement of this one. 169 00:08:50,440 --> 00:08:52,610 So the student engagement is much higher. 170 00:09:03,410 --> 00:09:06,350 Yeah, just as it's hard for a teacher in a tutorial setting 171 00:09:06,350 --> 00:09:09,840 to just talk for 50 minutes straight, it's also hard for a 172 00:09:09,840 --> 00:09:13,020 student in a tutorial session to surf the web for 50 minutes 173 00:09:13,020 --> 00:09:17,140 straight, or use their BlackBerry or read the 174 00:09:17,140 --> 00:09:19,780 newspaper or whatever it may be that the standard methods 175 00:09:19,780 --> 00:09:22,010 of lecture distraction are. 176 00:09:22,010 --> 00:09:22,900 Yes, can you tell me your name? 177 00:09:22,900 --> 00:09:25,325 AUDIENCE: Question about the conditions in these 178 00:09:25,325 --> 00:09:26,295 experiments. 179 00:09:26,295 --> 00:09:29,960 So normally in a university setting in this country, 180 00:09:29,960 --> 00:09:31,480 tutoring is something that students seek out for 181 00:09:31,480 --> 00:09:32,460 themselves. 182 00:09:32,460 --> 00:09:34,890 It's not something that's provided in lieu of lecture. 183 00:09:34,890 --> 00:09:37,760 Was that the case in this? 184 00:09:37,760 --> 00:09:40,160 Was it really just that the same material was covered in 185 00:09:40,160 --> 00:09:42,240 the same semester and they just did it two different 186 00:09:42,240 --> 00:09:44,490 ways, and everybody had to go to tutoring? 187 00:09:44,490 --> 00:09:47,210 PROFESSOR: Yeah, so what they did was-- 188 00:09:47,210 --> 00:09:49,250 I don't think these were university students. 189 00:09:49,250 --> 00:09:51,240 I think these were high school and even 190 00:09:51,240 --> 00:09:52,440 grade school students. 191 00:09:52,440 --> 00:09:53,600 Yeah. 192 00:09:53,600 --> 00:09:56,480 But what they did was they took the same number of 193 00:09:56,480 --> 00:09:59,545 teaching hours, and they either taught them in lecture 194 00:09:59,545 --> 00:10:02,100 or they taught them in tutorials, one-on-one, or I 195 00:10:02,100 --> 00:10:03,200 think sometimes one-on-two. 196 00:10:03,200 --> 00:10:06,355 AUDIENCE: So in both cases, they were required to go to 197 00:10:06,355 --> 00:10:07,000 class, in a sense. 198 00:10:07,000 --> 00:10:07,590 PROFESSOR: Yeah. 199 00:10:07,590 --> 00:10:08,890 I mean, I don't know if they actually 200 00:10:08,890 --> 00:10:10,220 went to the big class. 201 00:10:10,220 --> 00:10:13,670 But I'm sure they went to the tutorial class. 202 00:10:13,670 --> 00:10:15,420 That's partly of one of the differences. 203 00:10:15,420 --> 00:10:17,420 That's number six. 204 00:10:17,420 --> 00:10:19,292 Yes, way in the back. 205 00:10:19,292 --> 00:10:21,440 AUDIENCE: From experience, I've found that you know 206 00:10:21,440 --> 00:10:22,636 students don't understand something. 207 00:10:22,636 --> 00:10:24,975 You don't why until you sit down. 208 00:10:24,975 --> 00:10:27,380 Usually you find there's some gaping hole that's quite often 209 00:10:27,380 --> 00:10:28,790 easily plugged. 210 00:10:28,790 --> 00:10:29,340 PROFESSOR: OK. 211 00:10:29,340 --> 00:10:31,260 And how do you find that out? 212 00:10:31,260 --> 00:10:32,651 AUDIENCE: You start asking them, what class did you have? 213 00:10:32,651 --> 00:10:35,417 What did you not understand? 214 00:10:35,417 --> 00:10:37,463 And sometimes they'll just bubble [? right out, ?] 215 00:10:37,463 --> 00:10:39,660 I never got this one key concept. 216 00:10:39,660 --> 00:10:42,140 PROFESSOR: OK, so you can ask them questions, specific 217 00:10:42,140 --> 00:10:54,180 questions to figure out what they don't know, to diagnose 218 00:10:54,180 --> 00:10:55,430 what they're confused about. 219 00:11:01,250 --> 00:11:03,930 OK, let's take one more, and then I'll show you some 220 00:11:03,930 --> 00:11:08,280 methods that hopefully address what these characteristics-- 221 00:11:08,280 --> 00:11:10,250 these missing characteristics of group instruction. 222 00:11:10,250 --> 00:11:11,813 Yes? 223 00:11:11,813 --> 00:11:15,583 AUDIENCE: On one-on-one tutoring, for the student who 224 00:11:15,583 --> 00:11:18,430 might not be as into the effort [INAUDIBLE] added 225 00:11:18,430 --> 00:11:21,860 pressure, just feeling that there are other people 226 00:11:21,860 --> 00:11:24,310 [INAUDIBLE] 227 00:11:24,310 --> 00:11:27,740 student, there's no feeling of why I need to learn much more, 228 00:11:27,740 --> 00:11:28,990 [INAUDIBLE]. 229 00:11:31,560 --> 00:11:33,810 You don't really prepare yourself for anyone else. 230 00:11:33,810 --> 00:11:35,480 PROFESSOR: Right, so the method of teaching 231 00:11:35,480 --> 00:11:38,160 automatically adjusts to whatever level the student is. 232 00:11:38,160 --> 00:11:39,980 So they're not comparing to other people. 233 00:11:39,980 --> 00:11:42,250 They're are actually just comparing to what they don't 234 00:11:42,250 --> 00:11:43,710 know right then. 235 00:11:43,710 --> 00:11:47,630 So let's just call it intrinsic comparison with the 236 00:11:47,630 --> 00:11:50,015 knowledge, rather than extrinsic with other students. 237 00:12:02,280 --> 00:12:07,450 OK, so there's less emotional churn as a result of that. 238 00:12:07,450 --> 00:12:10,350 OK, so we could continue this list, but this is 239 00:12:10,350 --> 00:12:12,170 an excellent start. 240 00:12:12,170 --> 00:12:15,140 So now, if we look through that list, there's several 241 00:12:15,140 --> 00:12:16,060 themes that come out. 242 00:12:16,060 --> 00:12:19,070 I mean, it's hard in a group setting to figure out what 243 00:12:19,070 --> 00:12:20,230 students don't know. 244 00:12:20,230 --> 00:12:22,020 It's hard to ask them questions. 245 00:12:22,020 --> 00:12:24,560 It's hard to keep people engaged. 246 00:12:24,560 --> 00:12:27,980 It's easy to just talk at people as a teacher. 247 00:12:27,980 --> 00:12:32,280 So what can we do in group teaching to capture as many 248 00:12:32,280 --> 00:12:34,810 characteristics of this as we can? 249 00:12:34,810 --> 00:12:39,530 Well, I'll show you methods that I divide into four time 250 00:12:39,530 --> 00:12:43,810 scales, ranging from short to long. 251 00:12:43,810 --> 00:12:46,700 But before I do that, let me ask if there are any questions 252 00:12:46,700 --> 00:12:47,950 on anything so far. 253 00:12:51,240 --> 00:12:52,250 OK. 254 00:12:52,250 --> 00:12:53,391 You were first. 255 00:12:53,391 --> 00:12:54,864 AUDIENCE: How is student achievement measured? 256 00:12:54,864 --> 00:12:55,850 Is it just test scores? 257 00:12:55,850 --> 00:12:57,180 PROFESSOR: Yeah, that was a test score. 258 00:12:57,180 --> 00:13:02,080 So what they did is, actually they gave them a test. 259 00:13:02,080 --> 00:13:04,750 Like, if it was algebra, they gave them an algebra test, and 260 00:13:04,750 --> 00:13:07,580 then tested them at the end, and at the beginning too, just 261 00:13:07,580 --> 00:13:08,880 to see where they were to start with. 262 00:13:08,880 --> 00:13:10,630 AUDIENCE: So were the lectures more tailored to just teaching 263 00:13:10,630 --> 00:13:13,880 them algebra, and the tutoring was specifically tailored to 264 00:13:13,880 --> 00:13:15,380 doing problems in algebra? 265 00:13:15,380 --> 00:13:18,270 PROFESSOR: Well, the tutoring was whatever they needed to do 266 00:13:18,270 --> 00:13:19,110 well on the test. 267 00:13:19,110 --> 00:13:20,550 And the lecturing was hopefully 268 00:13:20,550 --> 00:13:21,840 designed that way too. 269 00:13:21,840 --> 00:13:25,340 But it had all the flaws of, you want to teach so students 270 00:13:25,340 --> 00:13:26,560 will do well on your final exam. 271 00:13:26,560 --> 00:13:28,530 But what do you do when you have 30 272 00:13:28,530 --> 00:13:31,310 diverse students in there? 273 00:13:31,310 --> 00:13:32,070 You had a question too. 274 00:13:32,070 --> 00:13:35,256 AUDIENCE: I was just wondering, do we know which of 275 00:13:35,256 --> 00:13:38,620 these particular suggestions are the most important, and 276 00:13:38,620 --> 00:13:41,020 which ones might be good? 277 00:13:41,020 --> 00:13:42,740 PROFESSOR: We have some idea. 278 00:13:42,740 --> 00:13:43,290 Good question. 279 00:13:43,290 --> 00:13:46,600 The question is which of these is most important, and which 280 00:13:46,600 --> 00:13:47,530 is less important. 281 00:13:47,530 --> 00:13:50,600 Actually, they're all getting at something similar. 282 00:13:50,600 --> 00:13:53,010 But there's a middle group in there, actually, that they 283 00:13:53,010 --> 00:13:56,380 studied, which was mastery learning. 284 00:13:56,380 --> 00:14:01,860 So mastery learning, it's just like a programmed instruction. 285 00:14:01,860 --> 00:14:03,610 So the idea is that-- 286 00:14:03,610 --> 00:14:05,480 Keller Plan is another word for it. 287 00:14:05,480 --> 00:14:08,190 So mastery learning is midway between tutoring and group 288 00:14:08,190 --> 00:14:09,010 instruction. 289 00:14:09,010 --> 00:14:11,860 There was one sigma better, so 84th percentile. 290 00:14:11,860 --> 00:14:15,910 So mastery learning, you don't go on to the new topics until 291 00:14:15,910 --> 00:14:18,540 you pass the mastery exam on the previous topic. 292 00:14:18,540 --> 00:14:20,810 So you're always building on a solid foundation. 293 00:14:20,810 --> 00:14:22,960 And so you work until you can pass the exam, and then you 294 00:14:22,960 --> 00:14:24,010 continue on. 295 00:14:24,010 --> 00:14:27,140 And just by adding that to group instruction, you get one 296 00:14:27,140 --> 00:14:28,370 sigma better. 297 00:14:28,370 --> 00:14:31,980 So right away, diagnosing misconceptions, you can see, 298 00:14:31,980 --> 00:14:32,700 is quite important. 299 00:14:32,700 --> 00:14:36,320 But there's still another one sigma to get. 300 00:14:36,320 --> 00:14:39,110 And so that's, I think, what all the rest of 301 00:14:39,110 --> 00:14:41,860 these items are about. 302 00:14:41,860 --> 00:14:44,540 And we do know a lot of stuff about how people learn. 303 00:14:44,540 --> 00:14:46,990 One of it is questions. 304 00:14:46,990 --> 00:14:48,280 Questions are essential. 305 00:14:48,280 --> 00:14:49,670 So I'm going to talk about that. 306 00:14:49,670 --> 00:14:51,380 But let me just ask again, any questions? 307 00:14:56,400 --> 00:14:56,800 OK, good. 308 00:14:56,800 --> 00:14:58,070 This time it worked. 309 00:14:58,070 --> 00:14:59,870 So now, what did I do? 310 00:14:59,870 --> 00:15:02,240 So this is actually the first method. 311 00:15:02,240 --> 00:15:05,315 So how long did I wait after I said, any questions? 312 00:15:09,030 --> 00:15:11,270 Half a second? 313 00:15:11,270 --> 00:15:11,740 One minute? 314 00:15:11,740 --> 00:15:14,280 No, five seconds. 315 00:15:14,280 --> 00:15:16,070 So the first time, I didn't wait five seconds, because 316 00:15:16,070 --> 00:15:20,100 actually a question came up a little before five seconds. 317 00:15:20,100 --> 00:15:22,630 But this time, the second time, I waited five seconds. 318 00:15:22,630 --> 00:15:23,360 Now, why is that? 319 00:15:23,360 --> 00:15:25,240 So that is the first method. 320 00:15:25,240 --> 00:15:27,850 When you ask a question-- 321 00:15:27,850 --> 00:15:30,460 for example, "any questions" or "what do you think about 322 00:15:30,460 --> 00:15:32,030 this"-- wait five seconds. 323 00:15:32,030 --> 00:15:33,570 And I'll explain why in a second. 324 00:15:33,570 --> 00:15:38,935 But, methods shortest to longest. 325 00:15:43,970 --> 00:15:49,240 The reason I divide them by shortest to longest is the 326 00:15:49,240 --> 00:15:50,650 shortest ones are the easiest to 327 00:15:50,650 --> 00:15:51,990 incorporate into your teaching. 328 00:15:51,990 --> 00:15:55,450 So anytime you teach, if you ask a question, wait five 329 00:15:55,450 --> 00:15:57,600 seconds, so the five-second time scale. 330 00:16:09,060 --> 00:16:10,990 OK, so why do I wait five seconds, 331 00:16:10,990 --> 00:16:13,030 and why not two seconds? 332 00:16:13,030 --> 00:16:16,970 Well, the reason is, think about your audience. 333 00:16:16,970 --> 00:16:19,800 Suppose you're talking away at them, and all the sudden you 334 00:16:19,800 --> 00:16:21,450 ask a question. 335 00:16:21,450 --> 00:16:23,280 Now, what are they hearing? 336 00:16:23,280 --> 00:16:26,810 So everyone's seen Charlie Brown? 337 00:16:26,810 --> 00:16:29,560 So what does Charlie Brown hear when he goes to school? 338 00:16:29,560 --> 00:16:32,790 Wah wah wah wah wah wah wah wah wah wah wah wah, and all 339 00:16:32,790 --> 00:16:34,515 of a sudden that changes and there's a question. 340 00:16:34,515 --> 00:16:36,845 It takes about a second to realize that the wah wah wah 341 00:16:36,845 --> 00:16:40,010 has stopped, and you're being asked a question. 342 00:16:40,010 --> 00:16:41,830 OK, so one second's gone. 343 00:16:41,830 --> 00:16:43,820 Let's call it that, the thumb-- one second. 344 00:16:43,820 --> 00:16:47,760 Now, it takes about another second to even figure out what 345 00:16:47,760 --> 00:16:49,270 the question is. 346 00:16:49,270 --> 00:16:51,340 Now you say, oh yeah, there's a question being asked. 347 00:16:51,340 --> 00:16:52,050 What did they say? 348 00:16:52,050 --> 00:16:54,710 OK, maybe now let's say it's one and a half seconds. 349 00:16:54,710 --> 00:16:58,070 So now we're at somewhere between two and three seconds. 350 00:16:58,070 --> 00:17:01,610 Now it takes maybe one or two more seconds to figure out 351 00:17:01,610 --> 00:17:02,980 what you're going to say about that. 352 00:17:02,980 --> 00:17:04,069 Do I have any thoughts about it? 353 00:17:04,069 --> 00:17:05,160 Do I actually have any questions? 354 00:17:05,160 --> 00:17:07,160 Do I have a thought about the thing they're asking me? 355 00:17:07,160 --> 00:17:10,150 Do I know what the band gap is in silicon, whatever the 356 00:17:10,150 --> 00:17:10,849 question may be? 357 00:17:10,849 --> 00:17:15,770 So now we're somewhere between four, maybe near five seconds. 358 00:17:15,770 --> 00:17:18,270 And then it maybe takes another second to get the 359 00:17:18,270 --> 00:17:21,430 courage up to raise your hand and be ready with a sentence. 360 00:17:21,430 --> 00:17:23,589 So now we're at least five seconds. 361 00:17:23,589 --> 00:17:27,310 So if you don't wait those five seconds, what you'll get 362 00:17:27,310 --> 00:17:30,200 is, you'll be getting a few questions, but you'll get 363 00:17:30,200 --> 00:17:31,940 questions from people who already thought about the 364 00:17:31,940 --> 00:17:34,490 material, in other words, the people who are already at the 365 00:17:34,490 --> 00:17:35,930 98th percentile. 366 00:17:35,930 --> 00:17:38,200 But if you want to bring everybody in, and get 367 00:17:38,200 --> 00:17:41,930 everybody thinking about it, you really need to wait, so 368 00:17:41,930 --> 00:17:45,020 you don't get questions just from the usual suspects. 369 00:17:45,020 --> 00:17:46,810 So wait five seconds. 370 00:17:46,810 --> 00:17:49,410 Now, the mechanism is quite important. 371 00:17:49,410 --> 00:17:51,980 If you just say, OK I'm going to wait five seconds, you'll 372 00:17:51,980 --> 00:17:54,380 go, any questions. 373 00:17:54,380 --> 00:17:56,960 Oh, done, five seconds is up. 374 00:17:56,960 --> 00:18:01,560 And you'll think five seconds is up in about one second. 375 00:18:01,560 --> 00:18:02,280 And why is that? 376 00:18:02,280 --> 00:18:05,510 Well, you're up in front of a whole bunch of people, and the 377 00:18:05,510 --> 00:18:07,100 adrenaline will be flowing. 378 00:18:07,100 --> 00:18:09,700 And adrenaline speeds up your time sense. 379 00:18:09,700 --> 00:18:12,420 All those stories about people who-- like mothers who saw 380 00:18:12,420 --> 00:18:15,070 their kid about to get hit by the car, they race out and 381 00:18:15,070 --> 00:18:17,780 grab the kid and the car keeps going. 382 00:18:17,780 --> 00:18:19,660 Maybe it screeches to a stop. 383 00:18:19,660 --> 00:18:20,975 They've managed to rescue their kid. 384 00:18:20,975 --> 00:18:23,930 Well, they could act much faster because adrenaline 385 00:18:23,930 --> 00:18:25,660 makes the time sense much sharper. 386 00:18:25,660 --> 00:18:29,820 So your idea of five seconds will be more like one second. 387 00:18:29,820 --> 00:18:33,570 There's another reason, which is there's this mistaken idea 388 00:18:33,570 --> 00:18:36,870 that if you're not talking, you're not teaching. 389 00:18:36,870 --> 00:18:38,740 So you're being paid to teach. 390 00:18:38,740 --> 00:18:41,370 And oh my god, you're not saying anything. 391 00:18:41,370 --> 00:18:43,600 That means you must not know something. 392 00:18:43,600 --> 00:18:46,790 So you feel insecure, and that increases the adrenaline and 393 00:18:46,790 --> 00:18:48,180 only speeds up the time problem more. 394 00:18:48,180 --> 00:18:51,530 So to wait five seconds, you actually have to count it -- 395 00:18:51,530 --> 00:18:56,620 one 1,000, two 1,000, three 1,000, four 1,000, five 1,000. 396 00:18:56,620 --> 00:18:59,460 And I actually sometimes just do it behind my back with my 397 00:18:59,460 --> 00:19:01,890 hand-- one 1,000, two 1,000, three 1,000, 398 00:19:01,890 --> 00:19:03,770 four 1,000, five 1,000. 399 00:19:03,770 --> 00:19:06,410 And it's not like you have to be watching the audience for 400 00:19:06,410 --> 00:19:08,040 the whole five seconds. 401 00:19:08,040 --> 00:19:11,075 It's actually better to wait the whole five seconds, and 402 00:19:11,075 --> 00:19:13,240 then choose one of the hands that has gone up rather than 403 00:19:13,240 --> 00:19:15,390 the first hand that goes up at two seconds. 404 00:19:15,390 --> 00:19:18,140 You say, oh, thank god, somebody asked a question. 405 00:19:18,140 --> 00:19:19,470 OK, now my waiting is over. 406 00:19:19,470 --> 00:19:22,220 Well, again, you'll be back in the usual suspect soup. 407 00:19:22,220 --> 00:19:28,640 So, first time scale for bringing in questions, in 408 00:19:28,640 --> 00:19:32,180 other words, spreading the engagement through the class. 409 00:19:32,180 --> 00:19:34,390 Because when people are asking questions, they're by 410 00:19:34,390 --> 00:19:35,730 definition engaged. 411 00:19:35,730 --> 00:19:37,070 They're struggling with the material. 412 00:19:37,070 --> 00:19:39,970 They're trying to make it their own. 413 00:19:39,970 --> 00:19:43,170 Wait five seconds. 414 00:19:43,170 --> 00:19:45,870 OK, the next method. 415 00:19:45,870 --> 00:19:51,000 So the next method is short time scale, one minute. 416 00:19:54,700 --> 00:19:59,160 And that is to use a feedback sheet at the end of every 417 00:19:59,160 --> 00:20:00,410 teaching session. 418 00:20:08,510 --> 00:20:11,400 So you actually have an example of a feedback sheet 419 00:20:11,400 --> 00:20:13,880 that we'll ask you to fill out at the end of this session, 420 00:20:13,880 --> 00:20:16,980 which we handed out at the beginning. 421 00:20:16,980 --> 00:20:22,460 And the blank versions of that sheet will also be on the TLL 422 00:20:22,460 --> 00:20:25,810 website, so you can actually download it, print it, and use 423 00:20:25,810 --> 00:20:28,090 it in your own teaching, as well as my notes 424 00:20:28,090 --> 00:20:28,820 on how to use it. 425 00:20:28,820 --> 00:20:32,030 But the main point is that at the end of the class, you give 426 00:20:32,030 --> 00:20:34,210 the students one or two minutes to fill 427 00:20:34,210 --> 00:20:35,590 out a feedback sheet. 428 00:20:35,590 --> 00:20:38,560 And what I've converged on is the following three questions 429 00:20:38,560 --> 00:20:42,950 on my feedback sheet, which is, what was most confusing? 430 00:20:42,950 --> 00:20:44,810 Basically, what question you have that 431 00:20:44,810 --> 00:20:46,550 still wasn't answered. 432 00:20:46,550 --> 00:20:50,980 Second question is, what was the most useful or most 433 00:20:50,980 --> 00:20:55,550 useless example or demonstration or teaching 434 00:20:55,550 --> 00:20:57,650 method that happened today? 435 00:20:57,650 --> 00:20:59,940 And the third question is, any other comments? 436 00:20:59,940 --> 00:21:03,280 So now let me explain why I use those three questions. 437 00:21:03,280 --> 00:21:06,610 The first question, these sheets are all anonymous. 438 00:21:06,610 --> 00:21:10,410 And it's a chance for someone, if they felt a little bit shy 439 00:21:10,410 --> 00:21:15,800 asking questions in front of people-- so here in the 440 00:21:15,800 --> 00:21:17,530 tutorial, one of the characteristics that was 441 00:21:17,530 --> 00:21:20,080 mentioned was that you don't feel nervous about asking a 442 00:21:20,080 --> 00:21:21,940 question, because there's no one there, or maybe there's 443 00:21:21,940 --> 00:21:23,310 one other person there. 444 00:21:23,310 --> 00:21:26,350 Whereas in a class of 30 or 80 or 20, you 445 00:21:26,350 --> 00:21:27,520 may feel a bit nervous. 446 00:21:27,520 --> 00:21:29,150 Well, if you feel a bit nervous, you just put your 447 00:21:29,150 --> 00:21:30,760 question on the feedback sheet. 448 00:21:30,760 --> 00:21:33,520 And so then at the beginning of the next session, I answer 449 00:21:33,520 --> 00:21:35,080 all the questions on the feedback sheets. 450 00:21:35,080 --> 00:21:38,010 So it takes me more than one minute, but actually not that 451 00:21:38,010 --> 00:21:39,270 much longer. 452 00:21:39,270 --> 00:21:41,120 Because you could flip through 100 453 00:21:41,120 --> 00:21:43,710 sheets in about 10 minutes. 454 00:21:43,710 --> 00:21:44,730 You just glance through. 455 00:21:44,730 --> 00:21:47,260 You'll see a bunch of questions are repeated. 456 00:21:47,260 --> 00:21:51,040 And you'll say, oh yeah, I do really need to explain that. 457 00:21:51,040 --> 00:21:54,310 And at the beginning in the next session, just explain all 458 00:21:54,310 --> 00:21:56,800 the important points. 459 00:21:56,800 --> 00:21:59,990 And that has another benefit, which is that it links back to 460 00:21:59,990 --> 00:22:02,550 the previous lecture, or the previous teaching session. 461 00:22:02,550 --> 00:22:05,000 So now you've made a thread between the previous session 462 00:22:05,000 --> 00:22:08,190 and the current one, and you got everyone up to speed into 463 00:22:08,190 --> 00:22:10,030 the space where you want them to be. 464 00:22:10,030 --> 00:22:11,830 So that's why I use the first question. 465 00:22:11,830 --> 00:22:15,250 The second question is, what worked? 466 00:22:15,250 --> 00:22:16,480 What didn't work? 467 00:22:16,480 --> 00:22:18,700 And I also had to add, and tell me whether it worked or 468 00:22:18,700 --> 00:22:19,180 didn't work. 469 00:22:19,180 --> 00:22:21,850 Because I used to get examples saying, that example. 470 00:22:21,850 --> 00:22:24,460 And I didn't know whether they loved it or hated it. 471 00:22:24,460 --> 00:22:26,640 So then I said, please tell me the sign of 472 00:22:26,640 --> 00:22:28,690 the effect as well. 473 00:22:28,690 --> 00:22:30,330 And then I would know. 474 00:22:30,330 --> 00:22:33,040 I would start to build a model of how students think and what 475 00:22:33,040 --> 00:22:34,100 works for them. 476 00:22:34,100 --> 00:22:35,910 So every time, basically, I learned that I brought in a 477 00:22:35,910 --> 00:22:38,330 demonstration, there was universal love 478 00:22:38,330 --> 00:22:39,980 on the second question. 479 00:22:39,980 --> 00:22:41,980 So I said, OK, that really connects with students. 480 00:22:41,980 --> 00:22:43,940 And I would make sure to do more of that. 481 00:22:43,940 --> 00:22:47,040 So it was reinforcement for me and practice for me at being a 482 00:22:47,040 --> 00:22:48,940 better teacher. 483 00:22:48,940 --> 00:22:52,130 And what you'll find is that as you use the sheet more and 484 00:22:52,130 --> 00:22:54,830 more, you get better and better at predicting how 485 00:22:54,830 --> 00:22:55,730 students think. 486 00:22:55,730 --> 00:22:58,390 So for example, you're doing some discussion on the board, 487 00:22:58,390 --> 00:23:00,640 some examples on derivation. 488 00:23:00,640 --> 00:23:05,300 And the first time you do it, maybe you don't know it's not 489 00:23:05,300 --> 00:23:06,100 going to go well. 490 00:23:06,100 --> 00:23:08,020 And then you read the sheet and you see, oh my god, I was 491 00:23:08,020 --> 00:23:08,860 a disaster. 492 00:23:08,860 --> 00:23:12,360 30 questions out of 80 all said, I didn't understand x. 493 00:23:12,360 --> 00:23:15,090 So now you understand that students didn't understand the 494 00:23:15,090 --> 00:23:15,920 way you did it. 495 00:23:15,920 --> 00:23:17,860 Well, now you've built a better model of 496 00:23:17,860 --> 00:23:19,250 how students think. 497 00:23:19,250 --> 00:23:21,840 So next time you're doing a derivation, what you'll find 498 00:23:21,840 --> 00:23:23,890 is-- at least what I've found is in the middle of the 499 00:23:23,890 --> 00:23:26,860 derivation, I'll realize, oh, this is not going well. 500 00:23:26,860 --> 00:23:27,850 I'm going to get a lot of questions 501 00:23:27,850 --> 00:23:29,240 about this on the sheet. 502 00:23:29,240 --> 00:23:30,700 Oops, but it's to late. 503 00:23:30,700 --> 00:23:31,850 I'm in the middle of the soup. 504 00:23:31,850 --> 00:23:33,570 I can't un-drink the soup. 505 00:23:33,570 --> 00:23:37,100 So I just finish the soup and just wait for the questions. 506 00:23:37,100 --> 00:23:40,010 But then after maybe another week of using the sheet, you 507 00:23:40,010 --> 00:23:41,960 actually have quite a good model of the students. 508 00:23:41,960 --> 00:23:44,620 And now before you start the derivation or when you're 509 00:23:44,620 --> 00:23:47,380 planning the lecture, you realize, oh yeah, that's not 510 00:23:47,380 --> 00:23:48,010 going to go well. 511 00:23:48,010 --> 00:23:49,590 Let me do it the other way, because I 512 00:23:49,590 --> 00:23:51,000 know that works better. 513 00:23:51,000 --> 00:23:54,140 So you'll find your model of the students developing more 514 00:23:54,140 --> 00:23:56,370 and more refinements and more and more accuracy. 515 00:23:56,370 --> 00:23:57,610 In other words, you're becoming 516 00:23:57,610 --> 00:23:59,240 a more expert teacher. 517 00:23:59,240 --> 00:24:01,030 And then the third question on the sheet 518 00:24:01,030 --> 00:24:03,410 is, any other comments? 519 00:24:03,410 --> 00:24:06,070 The reason for that is, it's just a free-form space. 520 00:24:06,070 --> 00:24:08,830 And I've actually had students say, oh, actually, when you 521 00:24:08,830 --> 00:24:12,050 explained that thing, you actually explained it wrong. 522 00:24:12,050 --> 00:24:13,230 I was like, oh that's good to know. 523 00:24:13,230 --> 00:24:14,850 So then in the beginning of the-- 524 00:24:14,850 --> 00:24:16,880 because we did it properly in this other class, and here's 525 00:24:16,880 --> 00:24:18,920 the exact reference that you maybe didn't know about. 526 00:24:18,920 --> 00:24:19,950 I was like, oh great. 527 00:24:19,950 --> 00:24:22,660 So at the beginning of the next class, I say, hey, one of 528 00:24:22,660 --> 00:24:25,980 you guys pointed out a mistake I made, and here is the 529 00:24:25,980 --> 00:24:27,290 corrected version. 530 00:24:27,290 --> 00:24:29,430 And people might not be willing to say that 531 00:24:29,430 --> 00:24:30,920 personally, because they say, oh my god, I don't want to 532 00:24:30,920 --> 00:24:32,790 correct the professor and make them feel stupid. 533 00:24:32,790 --> 00:24:36,020 But it's much easier to do it on an anonymous sheet. 534 00:24:36,020 --> 00:24:37,910 So I get really useful information on that. 535 00:24:37,910 --> 00:24:39,500 And sometimes you can figure out who did it, so you could 536 00:24:39,500 --> 00:24:42,480 send an email saying, oh thanks, that was useful. 537 00:24:42,480 --> 00:24:42,820 All right. 538 00:24:42,820 --> 00:24:43,500 [LAUGHTER] 539 00:24:43,500 --> 00:24:45,550 PROFESSOR: And it is. 540 00:24:45,550 --> 00:24:47,830 So you may think, oh no, you don't want to be corrected. 541 00:24:47,830 --> 00:24:50,840 But actually, after you tell the students the following 542 00:24:50,840 --> 00:24:54,930 enough, so it's again back to this. 543 00:24:54,930 --> 00:24:57,120 In a group, students feel like, oh my god, I don't want 544 00:24:57,120 --> 00:24:58,780 to make a mistake. 545 00:24:58,780 --> 00:25:01,540 So I give them the following speech quite often. 546 00:25:01,540 --> 00:25:03,560 Because if you don't make mistakes-- 547 00:25:03,560 --> 00:25:06,000 I tell them, look, how much did you know 548 00:25:06,000 --> 00:25:07,140 when you were born? 549 00:25:07,140 --> 00:25:07,960 Not a hell of a lot. 550 00:25:07,960 --> 00:25:08,870 You couldn't talk. 551 00:25:08,870 --> 00:25:10,110 You couldn't hardly walk. 552 00:25:10,110 --> 00:25:12,240 Well, how do you learn stuff? 553 00:25:12,240 --> 00:25:14,790 Did you just all the sudden start walking and talking? 554 00:25:14,790 --> 00:25:15,350 No. 555 00:25:15,350 --> 00:25:17,040 You mangled your grammar. 556 00:25:17,040 --> 00:25:19,720 You put "-ed" at the end of every past participle, even 557 00:25:19,720 --> 00:25:21,950 though some don't have that. 558 00:25:21,950 --> 00:25:24,040 And eventually you sorted it all out and you stood up 559 00:25:24,040 --> 00:25:25,300 straight and you walked. 560 00:25:25,300 --> 00:25:26,990 So basically, how did you learn? 561 00:25:26,990 --> 00:25:28,350 By making mistakes. 562 00:25:28,350 --> 00:25:30,530 So the only way to learn is to make mistakes. 563 00:25:30,530 --> 00:25:32,470 So if you don't make any mistakes, you will learn-- 564 00:25:32,470 --> 00:25:35,330 you'll know as much at the start of your class as at the 565 00:25:35,330 --> 00:25:35,870 end of the class. 566 00:25:35,870 --> 00:25:37,280 So you want to make mistakes. 567 00:25:37,280 --> 00:25:38,930 So I tell them that a bunch of times. 568 00:25:38,930 --> 00:25:41,920 But if then I'm really embarrassed about making 569 00:25:41,920 --> 00:25:43,930 mistakes, then I've defeated the whole purpose of telling 570 00:25:43,930 --> 00:25:44,700 students that. 571 00:25:44,700 --> 00:25:47,120 So I actually thank them whenever they point out 572 00:25:47,120 --> 00:25:49,980 something that I didn't do right. 573 00:25:49,980 --> 00:25:53,330 OK, so that's the second time scale. 574 00:25:53,330 --> 00:25:57,690 Now, the third time scale is not that much longer. 575 00:25:57,690 --> 00:25:59,830 It's about, let's say, four or five minutes. 576 00:26:03,440 --> 00:26:06,650 And it's a question which I'll call a conceptual multiple 577 00:26:06,650 --> 00:26:08,440 choice question. 578 00:26:08,440 --> 00:26:09,690 And I'll give you an example. 579 00:26:18,480 --> 00:26:21,740 OK, so here is the question that I'll use 580 00:26:21,740 --> 00:26:22,990 to illustrate it. 581 00:26:44,450 --> 00:26:47,680 Here is a pyramid with a square base. 582 00:26:47,680 --> 00:26:58,860 And it's B by B. The length of one side of the base is B. And 583 00:26:58,860 --> 00:27:02,120 the perpendicular height of the pyramid is H. OK, so 584 00:27:02,120 --> 00:27:03,370 what's the volume? 585 00:27:27,160 --> 00:27:32,070 OK, so does everyone understand the question? 586 00:27:32,070 --> 00:27:32,500 OK. 587 00:27:32,500 --> 00:27:35,340 Give it a try. 588 00:27:35,340 --> 00:27:37,510 Find your group or one or two. 589 00:27:37,510 --> 00:27:39,450 Any questions-- 590 00:27:39,450 --> 00:27:42,380 any confusions about the question? 591 00:27:42,380 --> 00:27:44,750 Don't give me any answers just yet, but any confusions about 592 00:27:44,750 --> 00:27:46,860 the question? 593 00:27:46,860 --> 00:27:51,680 OK, so find your groups of one or two other people, and we'll 594 00:27:51,680 --> 00:27:53,395 discuss that question in a couple minutes. 595 00:27:58,870 --> 00:28:02,620 Anyone want to say anything about this? 596 00:28:05,986 --> 00:28:07,530 Is there a section I haven't heard from? 597 00:28:07,530 --> 00:28:07,990 Yeah, go ahead. 598 00:28:07,990 --> 00:28:10,200 Can you just say your name? 599 00:28:10,200 --> 00:28:11,080 AUDIENCE: Brian. 600 00:28:11,080 --> 00:28:11,990 PROFESSOR: Brian, OK. 601 00:28:11,990 --> 00:28:15,080 So you like D but not the others? 602 00:28:15,080 --> 00:28:19,430 OK, can you tell me, for example, why you don't like A? 603 00:28:19,430 --> 00:28:22,990 AUDIENCE: Well, because all of them just have the wrong 604 00:28:22,990 --> 00:28:24,472 proportionality. 605 00:28:24,472 --> 00:28:27,975 If B increases, then the square is going to increase in 606 00:28:27,975 --> 00:28:29,500 area as B squared-- 607 00:28:29,500 --> 00:28:31,710 PROFESSOR: Ah, so you would like that to B squared. 608 00:28:31,710 --> 00:28:32,740 AUDIENCE: Right. 609 00:28:32,740 --> 00:28:35,590 PROFESSOR: Whereas it's just a single B and a single H. OK, 610 00:28:35,590 --> 00:28:37,970 so you don't like that because the proportionality is wrong. 611 00:28:37,970 --> 00:28:39,170 It doesn't scale correctly. 612 00:28:39,170 --> 00:28:41,390 So let me put here, bad scaling. 613 00:28:44,900 --> 00:28:45,720 What was another problem? 614 00:28:45,720 --> 00:28:47,150 AUDIENCE: It also has the wrong units. 615 00:28:47,150 --> 00:28:48,380 PROFESSOR: It has bogus units. 616 00:28:48,380 --> 00:28:52,198 OK, so it has bogus dimensions. 617 00:28:52,198 --> 00:28:53,680 AUDIENCE: [INAUDIBLE] dimensions. 618 00:28:53,680 --> 00:28:56,310 PROFESSOR: No, they're pretty much interchangeable. 619 00:28:56,310 --> 00:29:00,090 I use units to mean meters or feet or something, and 620 00:29:00,090 --> 00:29:01,460 dimensions to be things like length. 621 00:29:01,460 --> 00:29:04,160 But they're pretty much interchangeable in usage. 622 00:29:04,160 --> 00:29:07,990 So bad scaling, bad dimensions. 623 00:29:07,990 --> 00:29:10,660 OK, anyone have any comments about B? 624 00:29:10,660 --> 00:29:11,650 AUDIENCE: Same. 625 00:29:11,650 --> 00:29:12,710 PROFESSOR: Same problem. 626 00:29:12,710 --> 00:29:15,130 In fact, it's even more horrendous. 627 00:29:15,130 --> 00:29:18,220 Well, it starts out OK, I mean, at least as far as 628 00:29:18,220 --> 00:29:19,680 dimensions are concerned. 629 00:29:19,680 --> 00:29:21,100 But then what does it do? 630 00:29:21,100 --> 00:29:22,330 This has the wrong dimensions. 631 00:29:22,330 --> 00:29:24,740 That has the right dimensions, and then you add them. 632 00:29:24,740 --> 00:29:28,100 That's terrible. 633 00:29:28,100 --> 00:29:30,170 OK, so the dimensions are just bogus. 634 00:29:30,170 --> 00:29:31,330 Ah, OK. 635 00:29:31,330 --> 00:29:36,470 Can anyone say anything about choice C? 636 00:29:36,470 --> 00:29:37,458 Yeah? 637 00:29:37,458 --> 00:29:40,422 AUDIENCE: If you look at the extremes, like if you make H 638 00:29:40,422 --> 00:29:41,910 very small-- 639 00:29:41,910 --> 00:29:44,435 PROFESSOR: So if you stop on this pyramid and step on it 640 00:29:44,435 --> 00:29:47,826 until H goes to 0, what happens to the volume here? 641 00:29:47,826 --> 00:29:49,500 It goes to infinity. 642 00:29:49,500 --> 00:29:50,210 Yeah, it's terrible. 643 00:29:50,210 --> 00:29:52,260 So the extreme cases are just bogus. 644 00:29:56,810 --> 00:29:58,400 So it fails that test. 645 00:29:58,400 --> 00:30:02,500 OK, now we're back to D. So who likes D? 646 00:30:02,500 --> 00:30:03,440 So we have a few people who like D. 647 00:30:03,440 --> 00:30:04,810 [STUDENT CALLS OUT] 648 00:30:04,810 --> 00:30:08,010 [LAUGHTER] 649 00:30:08,010 --> 00:30:10,840 PROFESSOR: OK, go ahead. 650 00:30:10,840 --> 00:30:11,590 You don't like D. 651 00:30:11,590 --> 00:30:12,250 AUDIENCE: No, I don't like D. 652 00:30:12,250 --> 00:30:13,065 PROFESSOR: OK, why not? 653 00:30:13,065 --> 00:30:14,262 [LAUGHTER] 654 00:30:14,262 --> 00:30:16,734 AUDIENCE: It's the volume of the box, which has a size 655 00:30:16,734 --> 00:30:17,984 [INAUDIBLE]. 656 00:30:20,840 --> 00:30:22,990 PROFESSOR: So this is the volume of a box, in other 657 00:30:22,990 --> 00:30:24,360 words, if I had vertical sides. 658 00:30:24,360 --> 00:30:25,930 So let me draw vertical sides here. 659 00:30:29,350 --> 00:30:32,100 Right, so whereas the pyramid has actually got to be less. 660 00:30:32,100 --> 00:30:34,320 Now, it's kind of mysterious what this factor here should 661 00:30:34,320 --> 00:30:39,190 be, but it's definitely less than 1. 662 00:30:39,190 --> 00:30:41,600 So this is comparison with a box. 663 00:30:41,600 --> 00:30:44,030 So it has a good properties, and it's a good answer. 664 00:30:44,030 --> 00:30:45,260 It's just not correct. 665 00:30:45,260 --> 00:30:49,400 But that's OK, because it's important to realize what's 666 00:30:49,400 --> 00:30:51,200 good about it and what's not good about it. 667 00:30:51,200 --> 00:30:54,250 So it satisfies the extreme cases. 668 00:30:54,250 --> 00:30:55,660 It satisfies dimensions. 669 00:30:55,660 --> 00:30:56,680 It scales correctly. 670 00:30:56,680 --> 00:30:59,420 Like you pointed out, you want B squared, because it's the 671 00:30:59,420 --> 00:31:00,770 area down there. 672 00:31:00,770 --> 00:31:03,140 So it's good. 673 00:31:03,140 --> 00:31:04,240 It's not all good. 674 00:31:04,240 --> 00:31:07,390 Let's call it good mostly. 675 00:31:07,390 --> 00:31:13,050 But as they say, a miss is as good as a mile except in 676 00:31:13,050 --> 00:31:14,440 horseshoes and atom bombs. 677 00:31:16,990 --> 00:31:20,585 So good mostly, but box comparison. 678 00:31:24,870 --> 00:31:29,560 OK, so let me cross this guy out and this guy out 679 00:31:29,560 --> 00:31:30,830 and that guy out. 680 00:31:30,830 --> 00:31:32,710 So what do you conclude from that? 681 00:31:32,710 --> 00:31:34,770 They're all wrong. 682 00:31:34,770 --> 00:31:36,620 So here's another multiple choice question. 683 00:31:52,108 --> 00:31:53,560 [LAUGHTER] 684 00:31:53,560 --> 00:31:56,900 PROFESSOR: OK, so who votes for A? 685 00:31:56,900 --> 00:31:58,410 One of these is definitely correct. 686 00:31:58,410 --> 00:32:00,106 [LAUGHTER] 687 00:32:00,106 --> 00:32:01,750 PROFESSOR: No votes for A? 688 00:32:01,750 --> 00:32:02,940 Who votes for B? 689 00:32:02,940 --> 00:32:04,830 Oh, I'm hurt. 690 00:32:04,830 --> 00:32:05,530 I'm hurt. 691 00:32:05,530 --> 00:32:07,900 Well, B is in fact correct. 692 00:32:07,900 --> 00:32:09,680 [LAUGHTER] 693 00:32:09,680 --> 00:32:12,340 PROFESSOR: So every once in a while, I throw the students a 694 00:32:12,340 --> 00:32:16,280 curve ball and make all the choices wrong. 695 00:32:16,280 --> 00:32:19,990 Now, why would I do that, such an evil, dastardly thing? 696 00:32:19,990 --> 00:32:24,190 Well, it's good every once in a while to do that. 697 00:32:24,190 --> 00:32:27,210 In fact, I found that out experimentally, because the 698 00:32:27,210 --> 00:32:29,460 first time I used this question with the students, I 699 00:32:29,460 --> 00:32:31,360 was already using the feedback sheets. 700 00:32:31,360 --> 00:32:34,730 And on the feedback sheets, I got back tons of love on the 701 00:32:34,730 --> 00:32:35,910 comment sheets. 702 00:32:35,910 --> 00:32:38,590 The students said, oh, we love that, having 703 00:32:38,590 --> 00:32:40,350 all the answers wrong. 704 00:32:40,350 --> 00:32:42,160 Don't do it too often, but do it every once in a while, 705 00:32:42,160 --> 00:32:44,120 maybe once a month or so. 706 00:32:44,120 --> 00:32:46,350 And that way, they never know when it's coming, so they 707 00:32:46,350 --> 00:32:47,910 always have to check all the answers. 708 00:32:47,910 --> 00:32:50,210 They can't just do everything by elimination. 709 00:32:50,210 --> 00:32:52,510 So it is a very useful thing to do. 710 00:32:52,510 --> 00:32:54,630 There are other reasons for it too, and if you're curious, 711 00:32:54,630 --> 00:32:56,470 ask me in the questions, and I'll explain more 712 00:32:56,470 --> 00:32:57,320 reasons to do it. 713 00:32:57,320 --> 00:32:59,940 But that's already a sufficient reason. 714 00:32:59,940 --> 00:33:01,850 OK, so that's method three. 715 00:33:01,850 --> 00:33:05,460 And you see you get a bit of discussion. 716 00:33:05,460 --> 00:33:07,180 You get multiple choices. 717 00:33:07,180 --> 00:33:09,260 And what does that allow you to do right away? 718 00:33:09,260 --> 00:33:12,130 Well, what was one of the problems? 719 00:33:12,130 --> 00:33:14,760 Is, you can find out what misconception 720 00:33:14,760 --> 00:33:16,190 students have early. 721 00:33:16,190 --> 00:33:19,320 Point one up there, in a tutorial, you can 722 00:33:19,320 --> 00:33:20,740 ask students questions. 723 00:33:20,740 --> 00:33:23,220 Well, why not ask some questions in 724 00:33:23,220 --> 00:33:24,600 a big lecture too? 725 00:33:24,600 --> 00:33:26,200 So that's what we just did. 726 00:33:26,200 --> 00:33:26,990 So you can find out. 727 00:33:26,990 --> 00:33:30,250 If 90% of the students get it like that, you know you don't 728 00:33:30,250 --> 00:33:32,100 have to say much more about the topic. 729 00:33:32,100 --> 00:33:34,720 But if the answers are distributed at the monkey 730 00:33:34,720 --> 00:33:39,040 line, 25% for all the answers, then you know there's going to 731 00:33:39,040 --> 00:33:39,760 be trouble. 732 00:33:39,760 --> 00:33:42,570 And it's worth actually expanding on this point and 733 00:33:42,570 --> 00:33:45,500 the theme that question gets across right then in lecture. 734 00:33:45,500 --> 00:33:48,790 So you could make it much more tailored to the group of 735 00:33:48,790 --> 00:33:50,040 students you have. 736 00:33:52,450 --> 00:33:55,990 And the students also-- 737 00:33:55,990 --> 00:33:59,840 what happens in their small groups? 738 00:33:59,840 --> 00:34:02,180 Right, so remember we mentioned that in a tutorial, 739 00:34:02,180 --> 00:34:04,600 that it's a safe setting for raising questions, whereas a 740 00:34:04,600 --> 00:34:05,830 big group might not be. 741 00:34:05,830 --> 00:34:08,719 Well, what have we done by letting everyone work in 742 00:34:08,719 --> 00:34:10,060 groups of two or three? 743 00:34:10,060 --> 00:34:14,679 We've created a whole bunch of safe settings for questions. 744 00:34:14,679 --> 00:34:16,650 So the students are free to discuss in their 745 00:34:16,650 --> 00:34:17,480 groups of two or three. 746 00:34:17,480 --> 00:34:20,070 And if they can't resolve it there, well then they feel 747 00:34:20,070 --> 00:34:22,270 pretty confident that it's worthwhile sharing it with the 748 00:34:22,270 --> 00:34:22,810 whole class. 749 00:34:22,810 --> 00:34:24,540 Maybe the whole class can learn something 750 00:34:24,540 --> 00:34:25,790 from that as well. 751 00:34:29,330 --> 00:34:34,290 And that has another benefit, which is that it gets around 752 00:34:34,290 --> 00:34:36,020 the gender imbalance. 753 00:34:36,020 --> 00:34:40,920 So to illustrate this problem, I was once in a 754 00:34:40,920 --> 00:34:41,900 bookstore in New York. 755 00:34:41,900 --> 00:34:44,199 And I was standing in the computer section and this 756 00:34:44,199 --> 00:34:45,860 couple walked up the stairs. 757 00:34:45,860 --> 00:34:48,659 And the woman asked the man, oh, there's some 758 00:34:48,659 --> 00:34:49,820 big fat book on Java. 759 00:34:49,820 --> 00:34:51,750 And she said, what's Java? 760 00:34:51,750 --> 00:34:54,850 And within a millisecond, not batting an eyelid, he said, 761 00:34:54,850 --> 00:34:57,640 oh, it's the fastest search engine on the internet, which 762 00:34:57,640 --> 00:34:58,820 is completely rubbish. 763 00:34:58,820 --> 00:35:01,070 [LAUGHTER] 764 00:35:01,070 --> 00:35:02,390 PROFESSOR: It's a programming language. 765 00:35:02,390 --> 00:35:04,390 So it has absolutely nothing to do with a search engine. 766 00:35:04,390 --> 00:35:06,940 I'm sure no search engine is even written in Java. 767 00:35:06,940 --> 00:35:08,160 So it has nothing to do with search engines. 768 00:35:08,160 --> 00:35:09,810 So it's a complete lie. 769 00:35:09,810 --> 00:35:11,870 But he said it so fast. 770 00:35:11,870 --> 00:35:15,110 So there's a dichotomy there, which is-- generally speaking, 771 00:35:15,110 --> 00:35:17,020 it's called actually male answer syndrome. 772 00:35:17,020 --> 00:35:17,720 And the women-- 773 00:35:17,720 --> 00:35:18,170 [LAUGHTER] 774 00:35:18,170 --> 00:35:20,820 PROFESSOR: I see all the women laughing, or I hear all the 775 00:35:20,820 --> 00:35:21,430 women laughing. 776 00:35:21,430 --> 00:35:24,100 Well, what you'll find is generally, men are very 777 00:35:24,100 --> 00:35:28,010 willing to talk about stuff they know nothing about, 778 00:35:28,010 --> 00:35:31,830 speaking crudely in extreme caricatures, whereas women are 779 00:35:31,830 --> 00:35:34,610 reluctant to talk about stuff they even know about. 780 00:35:34,610 --> 00:35:39,020 So if you just ask a question to a group just flat out, even 781 00:35:39,020 --> 00:35:42,740 with the five-second wait, you're more likely to get 782 00:35:42,740 --> 00:35:46,430 responses from the guys than from the girls. 783 00:35:46,430 --> 00:35:51,120 So the way to try to mitigate that imbalance is to give 784 00:35:51,120 --> 00:35:53,980 people, first, a safe setting for asking questions. 785 00:35:53,980 --> 00:35:56,880 And then people actually calibrate to the correct level 786 00:35:56,880 --> 00:35:58,940 about, well, is this a reasonable idea? 787 00:35:58,940 --> 00:35:59,900 Is this not a reasonable idea? 788 00:35:59,900 --> 00:36:02,410 Could the people around me have good ideas about it? 789 00:36:02,410 --> 00:36:03,400 Is it resolved now? 790 00:36:03,400 --> 00:36:03,520 If 791 00:36:03,520 --> 00:36:06,190 Not, well, it's probably safe to raise in a bigger setting. 792 00:36:06,190 --> 00:36:08,730 So you'll actually fix the gender imbalance to a large 793 00:36:08,730 --> 00:36:11,220 extent, and balance it out. 794 00:36:11,220 --> 00:36:12,650 So it has lots of benefits that you get 795 00:36:12,650 --> 00:36:14,110 from tutorial teaching. 796 00:36:14,110 --> 00:36:18,360 So now I'll show you the last one, which we won't actually 797 00:36:18,360 --> 00:36:19,610 do for half an hour. 798 00:36:22,220 --> 00:36:25,580 But I want to sketch out how you could do a question for 799 00:36:25,580 --> 00:36:26,720 half an hour. 800 00:36:26,720 --> 00:36:28,940 I'll show you the kind of question that works in that 801 00:36:28,940 --> 00:36:30,880 time frame. 802 00:36:30,880 --> 00:36:32,840 So this could be multiple choice. 803 00:36:32,840 --> 00:36:35,405 Doesn't have to be, but some kind of conceptual question 804 00:36:35,405 --> 00:36:37,760 with lots of discussion. 805 00:36:37,760 --> 00:36:41,390 And often, it may have a demonstration. 806 00:36:41,390 --> 00:36:44,190 So let me show you that particular question. 807 00:36:44,190 --> 00:36:45,235 So I'm going to use-- 808 00:36:45,235 --> 00:36:47,480 I have these guys too, but I also have the wood blocks 809 00:36:47,480 --> 00:36:49,240 which I like so much. 810 00:36:49,240 --> 00:36:54,850 So here are two wood blocks cut for me by the machine shop 811 00:36:54,850 --> 00:36:56,470 of the Cambridge physics department 812 00:36:56,470 --> 00:36:57,390 when I taught there. 813 00:36:57,390 --> 00:37:01,280 So they cut them out of the same piece of pine, same 814 00:37:01,280 --> 00:37:02,450 grain, direction, everything. 815 00:37:02,450 --> 00:37:04,850 The only difference is this is 2 centimeters thick, and 816 00:37:04,850 --> 00:37:05,980 that's 1 centimeter thick. 817 00:37:05,980 --> 00:37:09,850 But They're both a foot long and 5 centimeters wide. 818 00:37:09,850 --> 00:37:15,332 So what I'm going to do is I'm going to tap this block, and 819 00:37:15,332 --> 00:37:16,511 you'll hear a note. 820 00:37:16,511 --> 00:37:19,810 [TAPS A NOTE ON WOOD BLOCK] 821 00:37:19,810 --> 00:37:21,060 PROFESSOR: Did everyone hear the note? 822 00:37:21,060 --> 00:37:21,630 Great. 823 00:37:21,630 --> 00:37:24,880 OK, so now the question is, when I tap this block, is the 824 00:37:24,880 --> 00:37:28,780 note going to be higher, the same frequency, or lower? 825 00:37:31,290 --> 00:37:34,210 OK, so does everyone understand the question? 826 00:37:38,210 --> 00:37:42,390 OK, so discuss with your neighbors. 827 00:37:42,390 --> 00:37:44,820 We'll take a vote in about a couple minutes. 828 00:37:44,820 --> 00:37:47,460 I won't give you the 10 minutes I would normally give 829 00:37:47,460 --> 00:37:49,560 people to discuss and argue. 830 00:37:49,560 --> 00:37:51,355 We'll take a couple reasons, then we'll do the experiment. 831 00:37:55,400 --> 00:38:02,010 OK, time to vote. 832 00:38:02,010 --> 00:38:06,680 So, just to sketch out how this could actually turn into 833 00:38:06,680 --> 00:38:11,120 a 30-minute question, normally I give students about a couple 834 00:38:11,120 --> 00:38:15,640 minutes to think on their own, then take a vote, and then set 835 00:38:15,640 --> 00:38:17,310 everyone to argue with each other. 836 00:38:17,310 --> 00:38:20,220 I say, in particular, find someone who has a different 837 00:38:20,220 --> 00:38:24,280 answer than you, and try to convince them of your answer. 838 00:38:24,280 --> 00:38:26,500 So then you get a big argument going. 839 00:38:26,500 --> 00:38:29,960 And so then I let that go for about 10 minutes. 840 00:38:29,960 --> 00:38:31,510 And then we take another vote. 841 00:38:31,510 --> 00:38:32,460 And then we discuss. 842 00:38:32,460 --> 00:38:35,000 So let's just imagine we've skipped forward to the end of 843 00:38:35,000 --> 00:38:37,670 the group discussion, and we're going to 844 00:38:37,670 --> 00:38:39,120 take the second vote. 845 00:38:39,120 --> 00:38:43,500 So who thinks the thick block will have a higher frequency 846 00:38:43,500 --> 00:38:44,750 than the thin block? 847 00:38:48,110 --> 00:38:52,110 About maybe 20 people. 848 00:38:52,110 --> 00:38:55,138 Who thinks they'll be equal? 849 00:38:55,138 --> 00:38:58,990 About 25. 850 00:38:58,990 --> 00:39:03,140 Who thinks the thick block will have a lower frequency? 851 00:39:03,140 --> 00:39:05,740 About 50. 852 00:39:05,740 --> 00:39:09,620 OK, so we have a good spread of opinion there. 853 00:39:09,620 --> 00:39:14,000 So now, again, in the scenario of the 30-minute question, I 854 00:39:14,000 --> 00:39:18,580 would ask for reasons, just like I did here, and I would 855 00:39:18,580 --> 00:39:20,330 just be the scribe. 856 00:39:20,330 --> 00:39:22,720 I would just write down people's reasons for A, B, or 857 00:39:22,720 --> 00:39:25,360 C, for greater, equal, or less than. 858 00:39:25,360 --> 00:39:26,935 Just make sure I understand the reason and 859 00:39:26,935 --> 00:39:27,780 then write it down. 860 00:39:27,780 --> 00:39:28,930 I don't have to agree with the reason. 861 00:39:28,930 --> 00:39:31,300 Just make sure I understand it, and the person who says it 862 00:39:31,300 --> 00:39:32,970 says, yeah, that's what I'm trying to say. 863 00:39:32,970 --> 00:39:34,870 Write it on the board. 864 00:39:34,870 --> 00:39:37,420 Then give people the opportunity to say a reason 865 00:39:37,420 --> 00:39:40,110 for any of the others or against any of them, or 866 00:39:40,110 --> 00:39:42,900 comment on any reason already on the board. 867 00:39:42,900 --> 00:39:45,400 And that can go for another 10 minutes or so, 868 00:39:45,400 --> 00:39:46,890 sometimes even longer. 869 00:39:46,890 --> 00:39:51,660 And then I ask people, OK, the test of science is experiment. 870 00:39:51,660 --> 00:39:54,170 Should we do the experiment? 871 00:39:54,170 --> 00:39:55,260 Should we do the experiment? 872 00:39:55,260 --> 00:39:55,790 AUDIENCE: Yes. 873 00:39:55,790 --> 00:39:56,340 PROFESSOR: OK. 874 00:39:56,340 --> 00:39:58,620 So just to remind you of the earlier tone. 875 00:40:02,113 --> 00:40:10,596 [TAPS A NOTE ON WOOD BLOCK] 876 00:40:10,596 --> 00:40:11,594 [TAPS A HIGHER NOTE ON WOOD BLOCK] 877 00:40:11,594 --> 00:40:14,300 [LAUGHTER] 878 00:40:14,300 --> 00:40:15,850 PROFESSOR: So the ayes have it. 879 00:40:20,130 --> 00:40:24,250 OK, so it turns out to be roughly almost a factor of two 880 00:40:24,250 --> 00:40:26,450 higher in frequency, almost a full octave. 881 00:40:26,450 --> 00:40:26,990 It's not quite. 882 00:40:26,990 --> 00:40:29,750 If they were infinitely thin, and this were twice infinitely 883 00:40:29,750 --> 00:40:32,850 thin, it would be exactly a factor of two. 884 00:40:32,850 --> 00:40:34,630 But because they have a finite thickness, 885 00:40:34,630 --> 00:40:35,910 it's not quite true. 886 00:40:35,910 --> 00:40:37,380 But that's how xylophones work. 887 00:40:37,380 --> 00:40:39,850 In fact, many people have reasoned their way to the 888 00:40:39,850 --> 00:40:41,655 correct answer by thinking about xylophones. 889 00:40:44,420 --> 00:40:46,980 And many people have reasoned their way to the incorrect 890 00:40:46,980 --> 00:40:49,830 answer by thinking about guitar strings, which brings 891 00:40:49,830 --> 00:40:52,710 up a very interesting discussion you can have. 892 00:40:52,710 --> 00:40:57,350 So what did you notice about here? 893 00:40:57,350 --> 00:41:00,725 When I was about to tap the second one, could 894 00:41:00,725 --> 00:41:02,060 you hear a pin drop? 895 00:41:02,060 --> 00:41:03,500 [LAUGHTER] 896 00:41:03,500 --> 00:41:03,710 PROFESSOR: Right. 897 00:41:03,710 --> 00:41:06,100 Student engagement is much higher, 898 00:41:06,100 --> 00:41:07,410 because people are involved. 899 00:41:07,410 --> 00:41:12,680 But the act of voting commits people to a public view. 900 00:41:12,680 --> 00:41:16,030 And they want to know, is this right or is this not right? 901 00:41:16,030 --> 00:41:19,820 And the act of voting has another benefit, which is that 902 00:41:19,820 --> 00:41:21,910 you get a much better error signal. 903 00:41:21,910 --> 00:41:23,500 Whereas, suppose you didn't vote. 904 00:41:23,500 --> 00:41:25,560 And suppose you thought, well, it could be higher because 905 00:41:25,560 --> 00:41:26,120 it's stiffer. 906 00:41:26,120 --> 00:41:29,110 On the other hand, it's bigger wavelengths, so it's lower. 907 00:41:29,110 --> 00:41:30,740 And you sort of both reasons in your head. 908 00:41:30,740 --> 00:41:32,440 You're in a superposition state. 909 00:41:32,440 --> 00:41:34,670 And then the experiment happens-- 910 00:41:34,670 --> 00:41:37,040 bing bing bing-- and it's higher, and you say, oh yeah, 911 00:41:37,040 --> 00:41:37,680 I knew that. 912 00:41:37,680 --> 00:41:41,910 It was higher because it's thicker and stiffer. 913 00:41:41,910 --> 00:41:44,400 So you think actually you understood everything, but you 914 00:41:44,400 --> 00:41:46,490 didn't actually figure out, well, which of these two 915 00:41:46,490 --> 00:41:48,100 reasons is right and why? 916 00:41:48,100 --> 00:41:51,130 Whereas if you have to publicly commit to one answer, 917 00:41:51,130 --> 00:41:54,830 then you get a clearly defined signal back about whether that 918 00:41:54,830 --> 00:41:55,870 answer was right or not. 919 00:41:55,870 --> 00:41:58,480 So it's very important to make sure people vote. 920 00:41:58,480 --> 00:42:00,840 And at the same time, it's very important to make sure 921 00:42:00,840 --> 00:42:03,450 people are not punished for voting. 922 00:42:03,450 --> 00:42:05,920 So does it matter in my classes whether people get the 923 00:42:05,920 --> 00:42:06,890 vote right or not? 924 00:42:06,890 --> 00:42:08,140 I just want them to vote. 925 00:42:08,140 --> 00:42:10,370 And so then I have to give my speech about, it's better to 926 00:42:10,370 --> 00:42:11,360 be wrong than right. 927 00:42:11,360 --> 00:42:12,331 Question? 928 00:42:12,331 --> 00:42:15,522 AUDIENCE: So I've been in lots of classes where the professor 929 00:42:15,522 --> 00:42:17,732 asks a question and waits a few seconds for people to 930 00:42:17,732 --> 00:42:18,714 raise their hands. 931 00:42:18,714 --> 00:42:23,296 And by the time he's done or she's done, there's a third of 932 00:42:23,296 --> 00:42:26,324 the class raising their hand, and those the people who had 933 00:42:26,324 --> 00:42:27,552 their hands up first. 934 00:42:27,552 --> 00:42:31,990 So how do you actually take that step? 935 00:42:31,990 --> 00:42:33,710 PROFESSOR: Sorry, could you tell me what they're doing? 936 00:42:33,710 --> 00:42:35,210 They ask a question. 937 00:42:35,210 --> 00:42:35,780 AUDIENCE: They ask a question-- 938 00:42:35,780 --> 00:42:38,662 PROFESSOR: Do they let the whole class discuss it? 939 00:42:38,662 --> 00:42:40,060 AUDIENCE: Not necessarily. 940 00:42:40,060 --> 00:42:42,390 So that's what you're saying is key here? 941 00:42:42,390 --> 00:42:43,960 PROFESSOR: Yeah, it's really key to let 942 00:42:43,960 --> 00:42:45,440 the whole class discuss-- 943 00:42:45,440 --> 00:42:48,830 so the normal structure for a long question like this one 944 00:42:48,830 --> 00:42:51,360 I'll do is I'll make sure everyone 945 00:42:51,360 --> 00:42:52,630 understands the question. 946 00:42:52,630 --> 00:42:55,820 And then I'll let people think by themselves for a minute or 947 00:42:55,820 --> 00:42:59,370 two, and take a vote after that, a straw poll, I call it, 948 00:42:59,370 --> 00:43:02,020 so people don't feel it's too weighty. 949 00:43:02,020 --> 00:43:03,790 The reason for that is that people have 950 00:43:03,790 --> 00:43:05,320 different learning styles. 951 00:43:05,320 --> 00:43:08,430 And some people want to think longer for themself, and some 952 00:43:08,430 --> 00:43:10,260 people want to just start talking right away, so I want 953 00:43:10,260 --> 00:43:12,480 to give something for everybody. 954 00:43:12,480 --> 00:43:15,450 And then after I take that vote, that gives me an idea 955 00:43:15,450 --> 00:43:18,090 where the class is, and it gives the class an idea of 956 00:43:18,090 --> 00:43:20,150 where they are, and who has different views. 957 00:43:20,150 --> 00:43:22,710 And then they can start arguing with each other. 958 00:43:22,710 --> 00:43:25,310 And so now they've had a lot of time to actually check what 959 00:43:25,310 --> 00:43:26,210 they all think. 960 00:43:26,210 --> 00:43:29,060 So people will have had arguments in their group that 961 00:43:29,060 --> 00:43:31,350 they can't resolve, so they're very eager to actually share 962 00:43:31,350 --> 00:43:32,590 the argument. 963 00:43:32,590 --> 00:43:35,090 Whereas if you just ask the question without giving people 964 00:43:35,090 --> 00:43:39,460 time to struggle with it, you're basically wasting the 965 00:43:39,460 --> 00:43:40,811 effect of the question. 966 00:43:40,811 --> 00:43:44,248 AUDIENCE: So how do you decide what level of difficulty for 967 00:43:44,248 --> 00:43:45,498 discussion? 968 00:43:47,880 --> 00:43:49,210 PROFESSOR: This is a hard question. 969 00:43:49,210 --> 00:43:50,280 But it's so rich. 970 00:43:50,280 --> 00:43:52,670 It has so many things. 971 00:43:52,670 --> 00:43:55,100 I don't expect most people to get the question right. 972 00:43:55,100 --> 00:43:57,780 In fact, when I ask this to faculty in physics department, 973 00:43:57,780 --> 00:43:59,630 when I give physics teaching seminars, most 974 00:43:59,630 --> 00:44:00,880 people get it wrong. 975 00:44:04,010 --> 00:44:06,690 I won't say all the places where that's been true, but 976 00:44:06,690 --> 00:44:09,440 it's been at many universities around the world. 977 00:44:09,440 --> 00:44:11,810 So I don't expect people to get it 978 00:44:11,810 --> 00:44:13,050 right, and I don't care. 979 00:44:13,050 --> 00:44:16,330 The reason for it is that it introduces so many ideas-- 980 00:44:16,330 --> 00:44:18,830 about, for example, spring models of solids. 981 00:44:18,830 --> 00:44:21,470 We can use musical instruments as analogies-- 982 00:44:21,470 --> 00:44:23,050 that I think it's worth spending even a 983 00:44:23,050 --> 00:44:24,370 whole class on it. 984 00:44:24,370 --> 00:44:28,840 And in fact, one time somebody said, well, but a xylophone, 985 00:44:28,840 --> 00:44:30,430 all the things are the same thickness and 986 00:44:30,430 --> 00:44:31,230 they're just longer. 987 00:44:31,230 --> 00:44:32,460 How does that work? 988 00:44:32,460 --> 00:44:33,880 And I said, oh, I'm glad you asked that. 989 00:44:33,880 --> 00:44:35,610 And I pulled out my daughter's xylophone-- 990 00:44:35,610 --> 00:44:36,900 she has a baby xylophone-- 991 00:44:36,900 --> 00:44:38,060 from my backpack. 992 00:44:38,060 --> 00:44:40,410 And so we analyzed the xylophone right there. 993 00:44:40,410 --> 00:44:42,580 So it leads to so many interesting things that I'm 994 00:44:42,580 --> 00:44:44,600 willing to spend a whole class on it. 995 00:44:44,600 --> 00:44:46,080 So that's how I decide how much time 996 00:44:46,080 --> 00:44:48,100 to allocate to something. 997 00:44:48,100 --> 00:44:51,340 If it's a really core idea, spend more time on it. 998 00:44:51,340 --> 00:44:53,910 And if it's peripheral, tend to spend less time on it or do 999 00:44:53,910 --> 00:44:58,270 a really short question on it, if at all. 1000 00:44:58,270 --> 00:44:59,450 And then the difficulty-- 1001 00:44:59,450 --> 00:45:01,500 I like to get questions, ideally-- 1002 00:45:01,500 --> 00:45:03,480 I mean, this one's different just because it's so rich-- 1003 00:45:03,480 --> 00:45:08,670 but ideally where students are sort of at 60% correct 1004 00:45:08,670 --> 00:45:12,510 thinking by themself, maybe 65%, even 70%. 1005 00:45:12,510 --> 00:45:15,295 Because even though they may be right, that sounds like oh, 1006 00:45:15,295 --> 00:45:16,410 they're mostly fine, but they may not 1007 00:45:16,410 --> 00:45:17,610 know why they're right. 1008 00:45:17,610 --> 00:45:21,290 So then in the discussion they can solidify their reasons and 1009 00:45:21,290 --> 00:45:22,840 maybe get up to 80% or 90%. 1010 00:45:22,840 --> 00:45:24,900 Whereas if you've got a question where they're 30% 1011 00:45:24,900 --> 00:45:27,400 correct to start with, and that doesn't have other 1012 00:45:27,400 --> 00:45:29,830 redeeming qualities like the richness of it, you'll just 1013 00:45:29,830 --> 00:45:33,540 propagate noise throughout the system, and just basically 1014 00:45:33,540 --> 00:45:35,650 wrong ideas will just spread all over and you'll spend all 1015 00:45:35,650 --> 00:45:37,220 your time correcting those. 1016 00:45:37,220 --> 00:45:39,280 So I gauge the difficulty based on 1017 00:45:39,280 --> 00:45:42,300 trying to hit that mark. 1018 00:45:42,300 --> 00:45:47,590 OK, so hopefully you've seen, first of all, 1019 00:45:47,590 --> 00:45:49,470 that tutorial teaching-- 1020 00:45:49,470 --> 00:45:50,890 the main points from today-- 1021 00:45:50,890 --> 00:45:53,490 is much more effective than regular teaching as normally 1022 00:45:53,490 --> 00:45:55,900 practiced because of these characteristics-- 1023 00:45:55,900 --> 00:45:59,045 generally questioning, feedback, instant feedback and 1024 00:45:59,045 --> 00:46:00,940 corrective feedback right away. 1025 00:46:00,940 --> 00:46:03,770 But through a series of methods, you can bring many of 1026 00:46:03,770 --> 00:46:06,720 the benefits of tutorial teaching to your own large 1027 00:46:06,720 --> 00:46:09,540 group teaching, which is the kind of teaching that most of 1028 00:46:09,540 --> 00:46:11,270 us will do, just for cost reasons. 1029 00:46:11,270 --> 00:46:13,730 So I wish you best of luck in all your teaching. 1030 00:46:13,730 --> 00:46:15,690 AUDIENCE: Can I just [? get ?] one interesting statement? 1031 00:46:15,690 --> 00:46:15,990 PROFESSOR: Sure. 1032 00:46:15,990 --> 00:46:19,420 AUDIENCE: It's something to think about, and faculty often 1033 00:46:19,420 --> 00:46:20,890 have difficulty with this. 1034 00:46:20,890 --> 00:46:24,888 There's probably a pretty high correlation between the amount 1035 00:46:24,888 --> 00:46:28,578 of information that you want to get through to students, 1036 00:46:28,578 --> 00:46:33,340 and the time that it takes to do it. 1037 00:46:33,340 --> 00:46:36,630 The more questions you ask, the less you can get through 1038 00:46:36,630 --> 00:46:37,420 the material. 1039 00:46:37,420 --> 00:46:39,240 And this constant questioning-- 1040 00:46:39,240 --> 00:46:40,210 PROFESSOR: This constant battle. 1041 00:46:40,210 --> 00:46:40,665 AUDIENCE: What should I do? 1042 00:46:40,665 --> 00:46:43,850 Should I just try to get this much information because I 1043 00:46:43,850 --> 00:46:45,470 want to ask lots of questions? 1044 00:46:45,470 --> 00:46:49,240 Or do I want to get that much information through, then I 1045 00:46:49,240 --> 00:46:51,590 better not spend too much time asking questions? 1046 00:46:51,590 --> 00:46:52,910 It's a conundrum. 1047 00:46:52,910 --> 00:46:55,280 I think asking questions is just a phenomenal way of 1048 00:46:55,280 --> 00:46:57,240 learning, but [INAUDIBLE]. 1049 00:46:57,240 --> 00:47:00,300 PROFESSOR: Yeah, basically we teach too much stuff. 1050 00:47:00,300 --> 00:47:01,860 And that's the fundamental problem. 1051 00:47:01,860 --> 00:47:05,380 And so one solution to that is to say, look, all the details, 1052 00:47:05,380 --> 00:47:06,660 get it from a book. 1053 00:47:06,660 --> 00:47:10,380 And in class, we're going to do what you can't easily do 1054 00:47:10,380 --> 00:47:14,200 from the book, which is struggle, argue, reason, and 1055 00:47:14,200 --> 00:47:15,110 correct those reasons. 1056 00:47:15,110 --> 00:47:16,520 That's hard to do from a book. 1057 00:47:16,520 --> 00:47:18,610 So you should use the class time for something that's 1058 00:47:18,610 --> 00:47:20,610 value added that you can't do elsewhere. 1059 00:47:20,610 --> 00:47:22,380 So good luck with that. 1060 00:47:22,380 --> 00:47:24,540 Please take a minute to fill out the feedback sheets. 1061 00:47:24,540 --> 00:47:27,420 And as long as no one kicks us out, I'll be here as long as 1062 00:47:27,420 --> 00:47:30,690 people have questions. 1063 00:47:30,690 --> 00:47:31,240 [? COMPUTER: Answers ?] 1064 00:47:31,240 --> 00:47:33,090 from lecture seven to questions 1065 00:47:33,090 --> 00:47:37,130 generated in lecture six. 1066 00:47:37,130 --> 00:47:43,020 PROFESSOR: OK, so questions from before. 1067 00:47:43,020 --> 00:47:46,660 What are your suggestions for someone teaching a course that 1068 00:47:46,660 --> 00:47:50,570 they are not expert in at all, you know, for the first time? 1069 00:47:50,570 --> 00:47:52,450 So I'm a practical man. 1070 00:47:52,450 --> 00:47:54,540 I know most people, when they're teaching a course, 1071 00:47:54,540 --> 00:47:57,210 teaching is not going to be their life. 1072 00:47:57,210 --> 00:48:00,090 I mean, it is for me, but that's unusual. 1073 00:48:00,090 --> 00:48:03,710 And if you love teaching, that's great. 1074 00:48:03,710 --> 00:48:07,520 But probably, your job will be dependent on how much research 1075 00:48:07,520 --> 00:48:11,420 you do or other activities like department committees. 1076 00:48:11,420 --> 00:48:14,110 And so you don't want to destroy your whole career on 1077 00:48:14,110 --> 00:48:15,810 your first course. 1078 00:48:15,810 --> 00:48:19,030 By which I mean, just try to survive your first course. 1079 00:48:19,030 --> 00:48:20,970 Because what you could do the first time you're teaching 1080 00:48:20,970 --> 00:48:22,300 it-- so the answer is, you need to 1081 00:48:22,300 --> 00:48:23,480 somehow become an expert. 1082 00:48:23,480 --> 00:48:25,400 If you want to teach it differently and creatively and 1083 00:48:25,400 --> 00:48:29,740 interestingly, you somehow need to become an expert. 1084 00:48:29,740 --> 00:48:33,910 Now, you could do that by spending the whole summer 1085 00:48:33,910 --> 00:48:36,940 before really figuring out the material from scratch. 1086 00:48:36,940 --> 00:48:38,890 And that probably in the long term is a good thing. 1087 00:48:38,890 --> 00:48:40,990 You'd probably find useful results in your 1088 00:48:40,990 --> 00:48:41,910 research from it. 1089 00:48:41,910 --> 00:48:44,790 But probably you don't have that summer to do that. 1090 00:48:44,790 --> 00:48:48,730 And so what you need to do is kill two birds with one stone 1091 00:48:48,730 --> 00:48:52,110 and become an expert by teaching it, in which case the 1092 00:48:52,110 --> 00:48:55,970 best plan I would recommend is just to teach it pretty much 1093 00:48:55,970 --> 00:48:58,030 the regular way, with some 1094 00:48:58,030 --> 00:48:59,740 interactive changes in lecture. 1095 00:48:59,740 --> 00:49:02,930 But just follow the regular plan, as much as it sticks in 1096 00:49:02,930 --> 00:49:03,830 one's craw. 1097 00:49:03,830 --> 00:49:06,220 Because in doing that, first of all, you will 1098 00:49:06,220 --> 00:49:08,280 be rocking the boat. 1099 00:49:08,280 --> 00:49:11,880 So people will accept it even if it's not great. 1100 00:49:11,880 --> 00:49:14,180 And you'll become an expert by the end. 1101 00:49:14,180 --> 00:49:16,720 And then the next time you teach it, you'll be OK. 1102 00:49:16,720 --> 00:49:19,530 Then you you've done that summer of thinking, but you've 1103 00:49:19,530 --> 00:49:21,390 done it during the class. 1104 00:49:21,390 --> 00:49:23,740 So it meant the first class didn't go as well as it could. 1105 00:49:23,740 --> 00:49:26,240 But it also meant you survived and you could order material 1106 00:49:26,240 --> 00:49:27,640 for your lab and all the other things that 1107 00:49:27,640 --> 00:49:28,890 you'd do in the summer. 1108 00:49:38,320 --> 00:49:39,300 How do you-- 1109 00:49:39,300 --> 00:49:41,790 so I like it when you emphasize that it's OK to get 1110 00:49:41,790 --> 00:49:42,965 the wrong answer. 1111 00:49:42,965 --> 00:49:46,730 It's like with the wood blocks, I mentioned how, 1112 00:49:46,730 --> 00:49:50,300 mostly when I ask this of physics professors too, people 1113 00:49:50,300 --> 00:49:51,960 get it mostly wrong. 1114 00:49:51,960 --> 00:49:54,750 And so I had another example of that in Colorado, because I 1115 00:49:54,750 --> 00:49:56,590 gave a talk using the wood blocks. 1116 00:49:56,590 --> 00:49:59,130 So how can you incorporate that "it's OK to be wrong, as 1117 00:49:59,130 --> 00:50:01,420 long as you learn" attitude into class? 1118 00:50:01,420 --> 00:50:04,500 One of the best ways is to minimize the amount of 1119 00:50:04,500 --> 00:50:07,840 grading, and the emphasis given to grading. 1120 00:50:07,840 --> 00:50:11,935 Grading, basically, as a first approximation-- 1121 00:50:19,750 --> 00:50:27,470 so if I just add two letters, it's hard to avoid that. 1122 00:50:27,470 --> 00:50:30,850 So grading, when you mark someone and you tell them, 1123 00:50:30,850 --> 00:50:36,320 bad, A B, C, D, well, the people who are getting B's, 1124 00:50:36,320 --> 00:50:40,640 C's, and D's, whatever the quote bad grades are, you are 1125 00:50:40,640 --> 00:50:42,490 actually shaming people. 1126 00:50:42,490 --> 00:50:45,210 And in some ways, you are degrading their psyche. 1127 00:50:45,210 --> 00:50:46,830 So it's not healthy. 1128 00:50:46,830 --> 00:50:48,440 So that is one of the political barriers to 1129 00:50:48,440 --> 00:50:50,270 educational change is the importance 1130 00:50:50,270 --> 00:50:52,030 that we give to grading. 1131 00:50:52,030 --> 00:50:55,040 And I will talk about that in the final session. 1132 00:50:55,040 --> 00:50:57,900 You may think, oh what about the people who get A's? 1133 00:50:57,900 --> 00:51:01,120 Well, if you're giving A, B, C's, and D's, the 1134 00:51:01,120 --> 00:51:02,810 people who get A's. 1135 00:51:02,810 --> 00:51:07,760 They may have struggled and were thinking, oh my god, will 1136 00:51:07,760 --> 00:51:08,180 I get an A? 1137 00:51:08,180 --> 00:51:09,140 Will I get an A? 1138 00:51:09,140 --> 00:51:11,400 Then they get an A. So they go, phew. 1139 00:51:11,400 --> 00:51:14,180 But still, they were nervous about their learning the whole 1140 00:51:14,180 --> 00:51:16,980 time instead of enjoying it as much as they could. 1141 00:51:16,980 --> 00:51:20,410 And second, there's also studies, many studies, which 1142 00:51:20,410 --> 00:51:22,800 show that when you reward people for things they already 1143 00:51:22,800 --> 00:51:24,770 enjoy-- this is totally fascinating-- 1144 00:51:24,770 --> 00:51:27,170 so when you reward people for things they already enjoy 1145 00:51:27,170 --> 00:51:30,360 doing, their enjoyment drops. 1146 00:51:30,360 --> 00:51:32,830 So if you start paying people for things that they would 1147 00:51:32,830 --> 00:51:36,260 like doing anyway, then they don't like it as much. 1148 00:51:36,260 --> 00:51:38,390 And you [INAUDIBLE] everyday examples of this. 1149 00:51:38,390 --> 00:51:41,980 You know if you know anyone who's a symphony orchestra 1150 00:51:41,980 --> 00:51:44,770 player, they say, oh yeah, the best way to start hating music 1151 00:51:44,770 --> 00:51:46,990 is to be a professional musician. 1152 00:51:46,990 --> 00:51:50,770 They love music, and then they had to do it for pay, in all 1153 00:51:50,770 --> 00:51:52,580 of a sudden they don't like as much anymore, not all of a 1154 00:51:52,580 --> 00:51:53,760 sudden, but slowly. 1155 00:51:53,760 --> 00:51:55,740 So there are many, many studies about that-- 1156 00:51:55,740 --> 00:51:56,620 motivation. 1157 00:51:56,620 --> 00:52:01,110 So what you want to do really is to find intrinsic 1158 00:52:01,110 --> 00:52:02,320 motivation. 1159 00:52:02,320 --> 00:52:04,660 And so the difference between extrinsic and intrinsic 1160 00:52:04,660 --> 00:52:06,290 motivation is fundamental. 1161 00:52:06,290 --> 00:52:09,280 And what you want to try to do is create the environment 1162 00:52:09,280 --> 00:52:11,450 always where the motivation is intrinsic, so that the 1163 00:52:11,450 --> 00:52:12,960 questions are interesting. 1164 00:52:12,960 --> 00:52:16,530 So what that means is you don't want to use bad 1165 00:52:16,530 --> 00:52:18,890 questions that people don't have an interest in, and then 1166 00:52:18,890 --> 00:52:20,940 force them to be interested because you give them 1167 00:52:20,940 --> 00:52:22,210 extrinsic motivation. 1168 00:52:22,210 --> 00:52:25,700 That's a fundamental bad choice, and then it's being 1169 00:52:25,700 --> 00:52:27,760 solved with the fundamental wrong approach. 1170 00:52:27,760 --> 00:52:30,280 What do you need to do is rather than do both of those, 1171 00:52:30,280 --> 00:52:32,000 you say, OK, let me find interesting questions that 1172 00:52:32,000 --> 00:52:33,200 people care about. 1173 00:52:33,200 --> 00:52:35,690 And then the intrinsic motivation carries people 1174 00:52:35,690 --> 00:52:37,450 through, whether they're right or wrong. 1175 00:52:37,450 --> 00:52:39,960 So that's why I like questions like the wood block so much, 1176 00:52:39,960 --> 00:52:41,620 because people are just actually interested. 1177 00:52:41,620 --> 00:52:42,790 They want to know. 1178 00:52:42,790 --> 00:52:44,010 They say, oh, that's a good question. 1179 00:52:44,010 --> 00:52:44,790 I should know that. 1180 00:52:44,790 --> 00:52:45,540 Oh, maybe I don't. 1181 00:52:45,540 --> 00:52:47,320 OK, well maybe I'll learn something. 1182 00:52:47,320 --> 00:52:50,140 So the other part of that is, if you notice, I didn't use 1183 00:52:50,140 --> 00:52:52,550 clickers when we did this question. 1184 00:52:52,550 --> 00:52:56,280 Partly, it's because clickers are expensive and you have a 1185 00:52:56,280 --> 00:52:59,220 bunch of logistics to do, and then you need probably some 1186 00:52:59,220 --> 00:53:02,660 ludicrous Windows program to receive the signals, and I 1187 00:53:02,660 --> 00:53:04,560 haven't written the Linux version for it. 1188 00:53:04,560 --> 00:53:06,210 So there's all of those issues. 1189 00:53:06,210 --> 00:53:09,430 Those are, I would say, not the fundamental issue. 1190 00:53:09,430 --> 00:53:11,360 The fundamental issue with clickers, why I don't like 1191 00:53:11,360 --> 00:53:17,610 them, is that they make people think they're being spied on. 1192 00:53:17,610 --> 00:53:20,240 So even especially if you live in a surveillance society, 1193 00:53:20,240 --> 00:53:23,850 where actually all your phone calls are being spied on, 1194 00:53:23,850 --> 00:53:26,790 people might think, well when you have clickers, you're 1195 00:53:26,790 --> 00:53:29,715 being spied on to know whether you got the right answer or 1196 00:53:29,715 --> 00:53:32,310 not, and it's going to count against you at some point. 1197 00:53:32,310 --> 00:53:35,520 So I'm very happy with people to just raise their hands. 1198 00:53:35,520 --> 00:53:39,320 And that's, in a way, more anonymous than a clicker that 1199 00:53:39,320 --> 00:53:40,650 belongs to you. 1200 00:53:40,650 --> 00:53:42,470 So there are ways of getting around that with clickers. 1201 00:53:42,470 --> 00:53:44,880 You can to have people trade clickers so they know that the 1202 00:53:44,880 --> 00:53:45,670 clickers are random. 1203 00:53:45,670 --> 00:53:47,290 So you can do things like that. 1204 00:53:47,290 --> 00:53:49,780 But still, I like the informal feel of, yeah, 1205 00:53:49,780 --> 00:53:50,670 just raise your hand. 1206 00:53:50,670 --> 00:53:50,970 Don't worry. 1207 00:53:50,970 --> 00:53:53,480 It's a safe space in the classroom. 1208 00:53:53,480 --> 00:53:55,160 And I have to say that a few times. 1209 00:53:55,160 --> 00:53:57,700 But just raise your hand, and don't worry. 1210 00:53:57,700 --> 00:53:58,630 And I'm not spying on you. 1211 00:53:58,630 --> 00:54:01,160 I don't care whether you get the right answer or not. 1212 00:54:01,160 --> 00:54:03,770 For example, with the wood blocks, I expect most people 1213 00:54:03,770 --> 00:54:04,770 to get the wrong answer. 1214 00:54:04,770 --> 00:54:06,260 That's OK. 1215 00:54:06,260 --> 00:54:08,960 We'll learn something about it afterwards. 1216 00:54:08,960 --> 00:54:11,180 So you do have to work at it, but there are things you can 1217 00:54:11,180 --> 00:54:13,820 do to keep the class [? safe. ?] 1218 00:54:13,820 --> 00:54:16,920 There are also things to do, which is that never-- 1219 00:54:16,920 --> 00:54:19,480 it's hard to remember how much power you have as the 1220 00:54:19,480 --> 00:54:24,380 instructor, and just as someone in 1221 00:54:24,380 --> 00:54:26,180 a position of authority. 1222 00:54:26,180 --> 00:54:29,580 So I might have told you the story from when I was a 1223 00:54:29,580 --> 00:54:31,652 graduate student, but it's worth telling again, if I 1224 00:54:31,652 --> 00:54:34,600 haven't, which is that I was giving a talk in a group 1225 00:54:34,600 --> 00:54:36,030 meeting when I was a graduate student. 1226 00:54:36,030 --> 00:54:37,780 My adviser got frustrated with me because I wasn't 1227 00:54:37,780 --> 00:54:41,190 understanding some fundamental point, actually about springs. 1228 00:54:41,190 --> 00:54:44,500 So to demonstrate it, he kicked the table at me and 1229 00:54:44,500 --> 00:54:46,390 said, is this acting like a spring? 1230 00:54:46,390 --> 00:54:47,550 And I was so shocked. 1231 00:54:47,550 --> 00:54:49,850 I was just mortified for like two days. 1232 00:54:49,850 --> 00:54:52,040 I just couldn't believe my adviser had done that in front 1233 00:54:52,040 --> 00:54:55,150 of everybody else, and thought that I must be 1234 00:54:55,150 --> 00:54:56,650 idiot and showed it. 1235 00:54:56,650 --> 00:54:59,010 So then eventually my fellow grad students said, well, 1236 00:54:59,010 --> 00:55:01,610 actually he does that only when you really cares. 1237 00:55:01,610 --> 00:55:04,580 So that's better than people just switching off. 1238 00:55:04,580 --> 00:55:06,880 So I sort of consoled myself with that. 1239 00:55:06,880 --> 00:55:10,240 But it did make a real strong impression on me, how much 1240 00:55:10,240 --> 00:55:13,960 even a small push from someone in authority can do. 1241 00:55:13,960 --> 00:55:18,330 So it's the same thing in lecture, if when someone says 1242 00:55:18,330 --> 00:55:22,560 something wrong, if you say, oh, why would 1243 00:55:22,560 --> 00:55:23,600 you have said that? 1244 00:55:23,600 --> 00:55:26,810 Even the slightest hint of that, people magnify and will 1245 00:55:26,810 --> 00:55:28,680 pick up and be very, very sensitive to. 1246 00:55:28,680 --> 00:55:32,350 So you have to be really, really, really careful not to 1247 00:55:32,350 --> 00:55:33,830 let that happen. 1248 00:55:33,830 --> 00:55:36,200 So one way is the poker face. 1249 00:55:36,200 --> 00:55:37,740 So I practiced the poker face. 1250 00:55:37,740 --> 00:55:40,480 So when people are making suggestions, for example, 1251 00:55:40,480 --> 00:55:43,620 about the wood block, why they would act one way or another, 1252 00:55:43,620 --> 00:55:46,840 I just make sure I get in a different mental state. 1253 00:55:46,840 --> 00:55:49,250 The mental state is transcription. 1254 00:55:49,250 --> 00:55:50,930 So I just want to make sure I understand 1255 00:55:50,930 --> 00:55:52,420 what people are saying. 1256 00:55:52,420 --> 00:55:54,340 And then I just write that down. 1257 00:55:54,340 --> 00:55:56,150 Now, it's even there you have to be careful. 1258 00:55:56,150 --> 00:55:59,040 Because you'll understand the correct answer quicker than 1259 00:55:59,040 --> 00:56:01,120 you will the incorrect answer. 1260 00:56:01,120 --> 00:56:02,690 So you have to make sure when people are explaining the 1261 00:56:02,690 --> 00:56:05,010 correct answer, you don't complete it for them. 1262 00:56:05,010 --> 00:56:07,600 And then in contrast, when people are explaining a wrong 1263 00:56:07,600 --> 00:56:09,710 answer, you ask lots of questions, because 1264 00:56:09,710 --> 00:56:10,980 that too is a signal. 1265 00:56:10,980 --> 00:56:15,970 So the poker face is tricky to do, but once you master it, 1266 00:56:15,970 --> 00:56:18,920 that's one good way of giving yourself a pause and not 1267 00:56:18,920 --> 00:56:21,680 criticizing people for their answers. 1268 00:56:21,680 --> 00:56:24,020 So there are various ways, but you just have to be careful. 1269 00:56:24,020 --> 00:56:27,170 And if you do that regularly, you'll find in a week or two, 1270 00:56:27,170 --> 00:56:30,240 you've overcome the presumption people have that 1271 00:56:30,240 --> 00:56:32,440 it's dangerous to ask questions. 1272 00:56:32,440 --> 00:56:33,690 But you do have to work at it. 1273 00:56:37,220 --> 00:56:39,470 Is it possible to incorporate mastery learning at the 1274 00:56:39,470 --> 00:56:40,500 college level? 1275 00:56:40,500 --> 00:56:41,850 So actually, there is a very interesting 1276 00:56:41,850 --> 00:56:42,850 experiment on that. 1277 00:56:42,850 --> 00:56:46,350 And it was done at MIT in the 1970s, I believe. 1278 00:56:46,350 --> 00:56:47,600 It was called-- 1279 00:57:00,080 --> 00:57:01,800 so it was called the Keller Plan. 1280 00:57:06,450 --> 00:57:08,100 I don't know if they did it for all courses, but the 1281 00:57:08,100 --> 00:57:10,860 physics courses were taught this way. 1282 00:57:10,860 --> 00:57:14,150 I don't know if only that way, or that was an option. 1283 00:57:14,150 --> 00:57:19,380 So it was in the 1970s, which was a time of-- 1284 00:57:19,380 --> 00:57:21,390 as people who were here then said, it was a 1285 00:57:21,390 --> 00:57:23,440 very turbulent time. 1286 00:57:23,440 --> 00:57:26,780 And the turbulence actually enabled lots of educational 1287 00:57:26,780 --> 00:57:30,550 experiments to happen, basically the '60s and '70s. 1288 00:57:30,550 --> 00:57:33,610 So if you look at, for example, the Feynman lectures 1289 00:57:33,610 --> 00:57:37,000 were in Caltech in the '60s, the Berkeley physics course, 1290 00:57:37,000 --> 00:57:41,310 1960s, things like the Keller Plan, the free schools at the 1291 00:57:41,310 --> 00:57:42,520 school level-- 1292 00:57:42,520 --> 00:57:45,420 tons of experiments happened in the '60s and '70s. 1293 00:57:45,420 --> 00:57:46,540 So the Keller Plan was one of them. 1294 00:57:46,540 --> 00:57:47,410 It was mastery learning. 1295 00:57:47,410 --> 00:57:49,630 Students worked on problems, and when they were ready for 1296 00:57:49,630 --> 00:57:52,100 the next piece, they continued. 1297 00:57:52,100 --> 00:57:55,320 And from what I can tell, it worked pretty well. 1298 00:57:55,320 --> 00:57:59,700 But then eventually it got killed off by basically 1299 00:57:59,700 --> 00:58:02,700 faculty who said, no, I'd rather teach and do lectures. 1300 00:58:02,700 --> 00:58:07,290 Because what's the point of the faculty if the students 1301 00:58:07,290 --> 00:58:09,460 can learn really well from the books? 1302 00:58:09,460 --> 00:58:13,710 So I think the Keller Plan was a really good idea. 1303 00:58:13,710 --> 00:58:18,680 In school, I learned for five years of high school math in 1304 00:58:18,680 --> 00:58:21,740 three or four weeks using the Keller Plan, compared to the 1305 00:58:21,740 --> 00:58:24,150 normal pace in school where you spend a whole year doing 1306 00:58:24,150 --> 00:58:25,240 trigonometry. 1307 00:58:25,240 --> 00:58:27,600 So the Keller Plan is a really, really excellent way, 1308 00:58:27,600 --> 00:58:29,760 if you have reasonable books. 1309 00:58:29,760 --> 00:58:32,850 So now, what are the full reasons it died? 1310 00:58:32,850 --> 00:58:33,630 I'm not really sure. 1311 00:58:33,630 --> 00:58:35,190 I need to check into that. 1312 00:58:35,190 --> 00:58:38,140 But people who were around then, some of them said, yeah, 1313 00:58:38,140 --> 00:58:41,560 just people who wanted to perform in lecture were really 1314 00:58:41,560 --> 00:58:44,010 sad about the Keller Plan and wanted to go 1315 00:58:44,010 --> 00:58:45,930 back to the old way. 1316 00:58:45,930 --> 00:58:48,320 And so when the political currents changed, so did the 1317 00:58:48,320 --> 00:58:49,570 Keller Plan. 1318 00:58:51,640 --> 00:58:54,560 How do I come up with these rich and interesting examples 1319 00:58:54,560 --> 00:58:56,600 like the wood blocks, and how often do 1320 00:58:56,600 --> 00:58:57,890 you incorporate demos? 1321 00:58:57,890 --> 00:59:00,650 Well, we'll talk about that in Walter Lewin's lecture. 1322 00:59:00,650 --> 00:59:02,920 So if you saw Walter Lewin's lecture, the one on the 1323 00:59:02,920 --> 00:59:05,870 pendulum, he must have had four or five different 1324 00:59:05,870 --> 00:59:07,980 demonstrations. 1325 00:59:07,980 --> 00:59:11,250 They were short, but he had many demonstrations. 1326 00:59:11,250 --> 00:59:15,030 And questions like this, if I had 20 of these, I would use 1327 00:59:15,030 --> 00:59:17,210 20 different ones. 1328 00:59:17,210 --> 00:59:22,360 So usually I have four or five of them that are a good long 1329 00:59:22,360 --> 00:59:24,780 time demo that are suitable for, say, half 1330 00:59:24,780 --> 00:59:25,860 a lecture or longer. 1331 00:59:25,860 --> 00:59:26,550 And I use them. 1332 00:59:26,550 --> 00:59:28,660 So wherever I can find them, I use them. 1333 00:59:28,660 --> 00:59:32,110 But not every single demo is worth spending 30 to 40 1334 00:59:32,110 --> 00:59:32,590 minutes on. 1335 00:59:32,590 --> 00:59:35,780 So you have to think about whether it teaches core ideas, 1336 00:59:35,780 --> 00:59:39,900 how it fits with the goals of your course. 1337 00:59:39,900 --> 00:59:43,560 So for example, let me talk through why I use this one. 1338 00:59:43,560 --> 00:59:46,450 Well, one of the goals that I want is I want students to be 1339 00:59:46,450 --> 00:59:48,870 able to make physical models themself. 1340 00:59:48,870 --> 00:59:51,270 I don't want them to just be able to solve equations that 1341 00:59:51,270 --> 00:59:52,220 I've put in front of them. 1342 00:59:52,220 --> 00:59:55,000 So normally what you do is you'd teach them the bending 1343 00:59:55,000 --> 00:59:57,640 beam equation, and then maybe you'd show them this, and then 1344 00:59:57,640 --> 00:59:59,120 you'd do this in two or three minutes. 1345 00:59:59,120 --> 01:00:01,510 But actually a much more interesting question is not, 1346 01:00:01,510 --> 01:00:03,580 what's the solution to the bending beam equation when the 1347 01:00:03,580 --> 01:00:05,060 beam's twice as thick. 1348 01:00:05,060 --> 01:00:08,970 The question is, what physical model is responsible for 1349 01:00:08,970 --> 01:00:09,820 making sound? 1350 01:00:09,820 --> 01:00:12,180 When you hear sound, where is it coming from? 1351 01:00:12,180 --> 01:00:15,000 When you tap this guy-- 1352 01:00:15,000 --> 01:00:17,380 [TAPS A NOTE ON WOOD BLOCK]-- why is it making sound, long 1353 01:00:17,380 --> 01:00:19,830 before you're even discussing the bending beam equation. 1354 01:00:19,830 --> 01:00:22,330 So that question is, to my mind, much more interesting. 1355 01:00:22,330 --> 01:00:25,590 And so I'm very willing to spend more time on that, and 1356 01:00:25,590 --> 01:00:28,940 having students develop that feel, and have them argue and 1357 01:00:28,940 --> 01:00:30,730 realize that there's different physical models. 1358 01:00:30,730 --> 01:00:32,890 It could be a standing wave in the block. 1359 01:00:32,890 --> 01:00:34,650 It could be that the block is bending. 1360 01:00:34,650 --> 01:00:36,990 How do you decide, and how do you decide which one you're 1361 01:00:36,990 --> 01:00:38,050 going to hear more? 1362 01:00:38,050 --> 01:00:40,450 And then for each one, how do you figure out how the 1363 01:00:40,450 --> 01:00:42,090 frequency's going to change? 1364 01:00:42,090 --> 01:00:45,620 So that, because it fits so well with the course goals, 1365 01:00:45,620 --> 01:00:47,176 spend more time on it. 1366 01:00:51,550 --> 01:00:55,590 Why is the stiffness a factor of eight bigger? 1367 01:00:55,590 --> 01:00:58,560 So that one, anyone who wants to know, I will 1368 01:00:58,560 --> 01:01:00,110 explain after lecture. 1369 01:01:00,110 --> 01:01:03,030 Just come to office hours. 1370 01:01:03,030 --> 01:01:06,850 So there's a simple picture using wood atoms. 1371 01:01:06,850 --> 01:01:08,100 Don't ask what wood atoms are. 1372 01:01:13,350 --> 01:01:16,100 How can you incorporate aspects of mastery learning 1373 01:01:16,100 --> 01:01:17,620 into regular teaching? 1374 01:01:17,620 --> 01:01:20,800 Ah, so that's what interactive teaching is all about. 1375 01:01:20,800 --> 01:01:24,590 So the reason mastery learning works so well is that you're 1376 01:01:24,590 --> 01:01:27,330 not building castles of knowledge on 1377 01:01:27,330 --> 01:01:30,740 sand, roughly speaking. 1378 01:01:30,740 --> 01:01:34,410 So normally what happens-- so the extreme case is Cambridge 1379 01:01:34,410 --> 01:01:35,050 in England. 1380 01:01:35,050 --> 01:01:37,700 So the teaching system there is you have an eight-week 1381 01:01:37,700 --> 01:01:40,810 term, and then you have a six-week break, and then an 1382 01:01:40,810 --> 01:01:43,990 eight-week term, six-week break, eight-week term, and 1383 01:01:43,990 --> 01:01:45,750 then 16-week break. 1384 01:01:45,750 --> 01:01:50,120 So the eight-week term, about what we would do in a semester 1385 01:01:50,120 --> 01:01:53,300 is compressed into eight weeks, just basically straight 1386 01:01:53,300 --> 01:01:55,160 dictation and lecture. 1387 01:01:55,160 --> 01:01:59,080 And the students have a hard time really understanding 1388 01:01:59,080 --> 01:02:01,750 everything at that pace, so they just take dictation. 1389 01:02:01,750 --> 01:02:03,830 And then you're supposed to figure everything else out, 1390 01:02:03,830 --> 01:02:06,540 integrate it in the six-week break. 1391 01:02:06,540 --> 01:02:10,130 So the problem with that is that it's very inefficient. 1392 01:02:10,130 --> 01:02:13,880 It's very inefficient because you haven't understood A. And 1393 01:02:13,880 --> 01:02:17,450 now B uses A, but A hasn't really been understood. 1394 01:02:17,450 --> 01:02:19,410 So you're not going to understand B. So now you have 1395 01:02:19,410 --> 01:02:21,310 A and B not really understood, so you just write them down. 1396 01:02:21,310 --> 01:02:23,870 Now C comes along using A and B, but A and B aren't 1397 01:02:23,870 --> 01:02:27,160 understood, so the problem compounds. 1398 01:02:27,160 --> 01:02:30,130 Whereas with mastery learning, only when you understand A do 1399 01:02:30,130 --> 01:02:33,660 you go onto B. And also when A and B are solid, then you go 1400 01:02:33,660 --> 01:02:37,780 onto C. So your knowledge castles are robust and strong. 1401 01:02:37,780 --> 01:02:40,440 And that's not true with most teaching. 1402 01:02:40,440 --> 01:02:42,760 So how do you remedy that problem? 1403 01:02:42,760 --> 01:02:44,740 Well one way is you ask questions in lecture. 1404 01:02:44,740 --> 01:02:48,730 So here, plan interactivity and build 1405 01:02:48,730 --> 01:02:49,980 it into your lecture. 1406 01:02:59,430 --> 01:03:02,710 So by asking students questions you figure out, oh, 1407 01:03:02,710 --> 01:03:06,330 if only 20% or 30% or maybe even 40% of the students knew 1408 01:03:06,330 --> 01:03:09,740 the correct answer, and even after discussion, you think, 1409 01:03:09,740 --> 01:03:11,790 oh, OK, well this is a fundamental concept. 1410 01:03:11,790 --> 01:03:13,940 Presumably that's why you asked the question about it. 1411 01:03:13,940 --> 01:03:15,380 But it wasn't mastered. 1412 01:03:15,380 --> 01:03:18,380 So better fix it, before you go on. 1413 01:03:18,380 --> 01:03:20,540 So that builds mastery learning into the regular 1414 01:03:20,540 --> 01:03:22,140 lecturing process. 1415 01:03:22,140 --> 01:03:23,740 And that's one reason that interactive 1416 01:03:23,740 --> 01:03:24,820 teaching is so effective. 1417 01:03:24,820 --> 01:03:27,650 So one of the other questions later in the sheets is, is 1418 01:03:27,650 --> 01:03:29,810 there evidence that interactive teaching is good 1419 01:03:29,810 --> 01:03:31,150 and helps people learn? 1420 01:03:31,150 --> 01:03:33,090 There is actually good evidence. 1421 01:03:33,090 --> 01:03:35,030 Maybe I should put some of those papers online. 1422 01:03:35,030 --> 01:03:37,690 One is by Richard Hake. 1423 01:03:37,690 --> 01:03:38,740 He's now retired. 1424 01:03:38,740 --> 01:03:40,800 He's physics professor from Indiana University. 1425 01:03:40,800 --> 01:03:47,090 So what he did is he did a sample of physics courses 1426 01:03:47,090 --> 01:03:49,880 across the country, intro physics courses that included 1427 01:03:49,880 --> 01:03:51,850 a total of 6,000 students. 1428 01:03:51,850 --> 01:03:55,550 And he asked the instructors to describe how they did 1429 01:03:55,550 --> 01:03:55,980 everything. 1430 01:03:55,980 --> 01:03:58,430 And then everything was grouped into either 1431 01:03:58,430 --> 01:04:00,770 interactive teaching or regular teaching. 1432 01:04:00,770 --> 01:04:04,880 And just the scores that students got on one particular 1433 01:04:04,880 --> 01:04:06,340 exam, which was a force concept 1434 01:04:06,340 --> 01:04:08,010 inventory, before and after-- 1435 01:04:08,010 --> 01:04:09,860 they were given the force concept inventory before the 1436 01:04:09,860 --> 01:04:11,430 class started and at the end-- 1437 01:04:11,430 --> 01:04:14,070 they saw how much the students improved. 1438 01:04:14,070 --> 01:04:16,730 OK, so if you improved 100%-- 1439 01:04:16,730 --> 01:04:19,356 in other words, suppose you started at 20% correct and you 1440 01:04:19,356 --> 01:04:20,340 got to 100%-- 1441 01:04:20,340 --> 01:04:22,910 that was considered a 1.0 gain. 1442 01:04:22,910 --> 01:04:28,540 If you went from 20% percent to 60%, that mean you got 1443 01:04:28,540 --> 01:04:30,870 halfway to the maximum possible score you could have 1444 01:04:30,870 --> 01:04:32,600 gotten, so half of the maximum improvement, that 1445 01:04:32,600 --> 01:04:33,800 was a gain of 0.5. 1446 01:04:33,800 --> 01:04:35,740 So he measured the gain for everybody. 1447 01:04:46,610 --> 01:04:53,660 So this is the gain on the force concept inventory. 1448 01:04:53,660 --> 01:04:56,640 And this is the number of courses in each area. 1449 01:04:56,640 --> 01:04:59,810 So it was roughly like that. 1450 01:04:59,810 --> 01:05:03,060 So this was the regular. 1451 01:05:03,060 --> 01:05:05,620 So the regular teaching, by the way, included fantastic 1452 01:05:05,620 --> 01:05:08,380 teachers, people who were rated highest lecturer in the 1453 01:05:08,380 --> 01:05:11,560 university and had won lecturing awards. 1454 01:05:11,560 --> 01:05:16,330 And the interactive teaching was something like this. 1455 01:05:16,330 --> 01:05:19,670 I'll put the paper online so you can see the exact graph. 1456 01:05:19,670 --> 01:05:22,840 But basically, the worst interactive teaching was 1457 01:05:22,840 --> 01:05:25,810 better than most of the regular teaching. 1458 01:05:25,810 --> 01:05:27,880 And the regular teaching hardly got 1459 01:05:27,880 --> 01:05:32,300 better than 0.2 or 0.3. 1460 01:05:32,300 --> 01:05:34,810 So if you wanted any more gain than that, you really needed 1461 01:05:34,810 --> 01:05:36,220 to do interactive methods. 1462 01:05:36,220 --> 01:05:38,860 And I think that is because you've incorporated mastery 1463 01:05:38,860 --> 01:05:40,130 learning into the curriculum. 1464 01:05:44,320 --> 01:05:46,410 OK, what do you do when the students are really quite and 1465 01:05:46,410 --> 01:05:48,840 won't answer your questions? 1466 01:05:48,840 --> 01:05:53,450 Or flip side is, what if only the quote 5% usual suspects 1467 01:05:53,450 --> 01:05:54,960 are the ones answering the questions? 1468 01:05:54,960 --> 01:05:56,160 What do you do? 1469 01:05:56,160 --> 01:06:02,490 Well, so that is related to the question of, are there bad 1470 01:06:02,490 --> 01:06:04,710 ways of incorporating interactivity? 1471 01:06:04,710 --> 01:06:05,500 And there are. 1472 01:06:05,500 --> 01:06:10,010 The worst is the following, which is-- 1473 01:06:10,010 --> 01:06:11,260 I'll sort of parody it. 1474 01:06:16,090 --> 01:06:19,470 So we're doing relativity, or nuclear physics. 1475 01:06:19,470 --> 01:06:22,160 E equals MC-- 1476 01:06:22,160 --> 01:06:24,660 [LAUGHTER] 1477 01:06:24,660 --> 01:06:26,000 PROFESSOR: Squared, yeah. 1478 01:06:26,000 --> 01:06:27,020 OK. 1479 01:06:27,020 --> 01:06:31,750 So you'll find a lot of people who normally wouldn't teach 1480 01:06:31,750 --> 01:06:35,310 interactively are now, they're told or they hear that it's 1481 01:06:35,310 --> 01:06:37,680 good to teach interactively and ask students questions. 1482 01:06:37,680 --> 01:06:40,670 But if you don't have any practice in how to do that, 1483 01:06:40,670 --> 01:06:43,850 the easiest questions to ask are just things like this. 1484 01:06:43,850 --> 01:06:46,520 And the problem with that is not that 1485 01:06:46,520 --> 01:06:47,830 they're asking a question. 1486 01:06:47,830 --> 01:06:49,090 It's good to ask a question. 1487 01:06:49,090 --> 01:06:54,000 But the problem is that this thing, this two, is just a 1488 01:06:54,000 --> 01:06:54,980 memorized fact. 1489 01:06:54,980 --> 01:06:58,170 So it's possible to answer it just by memory, whereas if 1490 01:06:58,170 --> 01:07:02,430 there was actually some debate about what it should be, you 1491 01:07:02,430 --> 01:07:04,350 could ask the students the question. 1492 01:07:04,350 --> 01:07:07,500 But now, if you just ask people question like that, and 1493 01:07:07,500 --> 01:07:09,710 you give people no time to think, yes, you will get 1494 01:07:09,710 --> 01:07:13,410 answers just from the quote top 5%, the usual suspects. 1495 01:07:13,410 --> 01:07:16,340 So to avoid that, what you need to do is give people a 1496 01:07:16,340 --> 01:07:18,520 chance to think on their own. 1497 01:07:18,520 --> 01:07:21,330 So that's one of the interactive teaching 1498 01:07:21,330 --> 01:07:24,060 techniques, the idea of give people a minute or even 30 1499 01:07:24,060 --> 01:07:28,140 seconds to think on their own, so that you'll get answers 1500 01:07:28,140 --> 01:07:30,200 from a wider spectrum of people, because they've 1501 01:07:30,200 --> 01:07:32,140 checked it out with their neighbor. 1502 01:07:32,140 --> 01:07:35,580 And they feel safer in volunteering and answer or 1503 01:07:35,580 --> 01:07:37,740 asking a question about it. 1504 01:07:37,740 --> 01:07:41,250 So that's how you avoid two things, two problems at once. 1505 01:07:41,250 --> 01:07:43,670 You avoid the quiet students, because you've given-- those 1506 01:07:43,670 --> 01:07:45,450 students are being quiet because you've given people a 1507 01:07:45,450 --> 01:07:46,660 chance to think. 1508 01:07:46,660 --> 01:07:50,550 And you also avoid the problem of just the usual people 1509 01:07:50,550 --> 01:07:51,460 answering, because you've given 1510 01:07:51,460 --> 01:07:52,710 everybody a chance to think. 1511 01:07:57,280 --> 01:08:01,150 OK, if we don't really understand until we teach, 1512 01:08:01,150 --> 01:08:03,890 should we have students teach each other in presentations, 1513 01:08:03,890 --> 01:08:07,090 or is that not worth the time? 1514 01:08:07,090 --> 01:08:10,740 My feeling is that huge big presentations and having 1515 01:08:10,740 --> 01:08:14,540 students present to each other is not so much worth the time. 1516 01:08:14,540 --> 01:08:18,750 I mean, it's worth the time of the one person who's doing the 1517 01:08:18,750 --> 01:08:19,979 presentation. 1518 01:08:19,979 --> 01:08:22,330 But that's the main person who learns in 1519 01:08:22,330 --> 01:08:23,359 that teaching session. 1520 01:08:23,359 --> 01:08:25,870 So there are several graduate seminars, many I took as a 1521 01:08:25,870 --> 01:08:28,330 graduate student, that are run the following way. 1522 01:08:28,330 --> 01:08:31,290 The professor just sits back and each time-- 1523 01:08:31,290 --> 01:08:34,410 they assign a list of topics, and each student volunteers 1524 01:08:34,410 --> 01:08:37,399 for one topic to present to everybody else. 1525 01:08:37,399 --> 01:08:40,450 Now, that is a fantastic way to learn one topic in the 1526 01:08:40,450 --> 01:08:41,720 entire course. 1527 01:08:41,720 --> 01:08:43,140 And it does work for that. 1528 01:08:43,140 --> 01:08:45,800 And part of my Ph.D. Came out of one of the topics that I 1529 01:08:45,800 --> 01:08:48,090 learned from one of those courses, because I really 1530 01:08:48,090 --> 01:08:50,529 wanted to figure it out. 1531 01:08:50,529 --> 01:08:51,640 So it can work. 1532 01:08:51,640 --> 01:08:52,649 And it does work in some ways. 1533 01:08:52,649 --> 01:08:55,350 But it's not a very efficient way, because all the other 1534 01:08:55,350 --> 01:08:56,960 people are just basically passive. 1535 01:08:56,960 --> 01:08:58,439 Yeah, they read the stuff. 1536 01:08:58,439 --> 01:09:00,760 But now they're being taught by someone who's just barely 1537 01:09:00,760 --> 01:09:04,649 mastering the field and is not likely to teach interactively 1538 01:09:04,649 --> 01:09:06,560 with a large margin of safety. 1539 01:09:06,560 --> 01:09:09,540 So it's much better to have students teach each other by 1540 01:09:09,540 --> 01:09:13,200 having them argue with each other on small time scale. 1541 01:09:13,200 --> 01:09:15,750 So for example, if you remember in the wood blocks, I 1542 01:09:15,750 --> 01:09:18,950 said, OK, are you with your neighbor about your answer? 1543 01:09:18,950 --> 01:09:22,020 Well, now the students are trying to teach each other. 1544 01:09:22,020 --> 01:09:25,560 Some students think, oh yeah, it's due to the bending. 1545 01:09:25,560 --> 01:09:27,840 OK, well that turns out to be correct. 1546 01:09:27,840 --> 01:09:29,250 But can you convince your neighbor? 1547 01:09:29,250 --> 01:09:30,850 Well, in trying to convince your neighbor, 1548 01:09:30,850 --> 01:09:32,760 you are doing teaching. 1549 01:09:32,760 --> 01:09:34,950 You're trying to figure out, what's a way that you can do 1550 01:09:34,950 --> 01:09:36,729 it without writing down 50 equations. 1551 01:09:36,729 --> 01:09:38,729 That's exactly what you want to do in teaching. 1552 01:09:38,729 --> 01:09:41,290 So I think it's a much better way, is to build the 1553 01:09:41,290 --> 01:09:44,590 interactivity into the class for everybody, rather than 1554 01:09:44,590 --> 01:09:47,130 having it as a rotating seminar where just one person 1555 01:09:47,130 --> 01:09:48,380 at a time learns. 1556 01:09:54,630 --> 01:09:56,880 In organizing big ideas into a tree, there are 1557 01:09:56,880 --> 01:09:58,730 often multiple ways-- 1558 01:09:58,730 --> 01:10:00,890 for example, you can do current understanding versus 1559 01:10:00,890 --> 01:10:03,670 history, or experiment versus theory-- and it's often good 1560 01:10:03,670 --> 01:10:06,260 for students to know more than one of these organizations. 1561 01:10:06,260 --> 01:10:08,540 How do you do that in a course design? 1562 01:10:08,540 --> 01:10:12,780 Yeah, so unfortunately there's only one time dimension. 1563 01:10:12,780 --> 01:10:14,120 There's three space dimensions, but 1564 01:10:14,120 --> 01:10:15,180 only one time dimension. 1565 01:10:15,180 --> 01:10:18,560 So the course has to evolve in one dimension somehow. 1566 01:10:18,560 --> 01:10:20,610 So you need at least one organization. 1567 01:10:20,610 --> 01:10:21,490 But you're right. 1568 01:10:21,490 --> 01:10:23,680 You need other organizations as well. 1569 01:10:23,680 --> 01:10:28,030 So the way I square that circle is as follows. 1570 01:10:35,690 --> 01:10:37,486 So let's say time goes that way. 1571 01:10:42,530 --> 01:10:43,650 So this is unit one. 1572 01:10:43,650 --> 01:10:45,820 Let's say it's one technique, one mode of reasoning, 1573 01:10:45,820 --> 01:10:46,840 dimensional analysis. 1574 01:10:46,840 --> 01:10:48,140 Let's say this is another mode of reasoning, 1575 01:10:48,140 --> 01:10:49,820 conservation, and so on. 1576 01:10:49,820 --> 01:10:51,580 So these are units. 1577 01:10:51,580 --> 01:10:52,610 And now you have topics. 1578 01:10:52,610 --> 01:10:54,640 Well, what I like to do is I want to show other 1579 01:10:54,640 --> 01:10:55,440 organizations. 1580 01:10:55,440 --> 01:10:56,630 And why is that good? 1581 01:10:56,630 --> 01:10:58,660 Well, what you're doing is you're connecting. 1582 01:10:58,660 --> 01:11:00,230 You're building threads across. 1583 01:11:00,230 --> 01:11:00,660 And you're right. 1584 01:11:00,660 --> 01:11:01,970 You definitely want to do that. 1585 01:11:01,970 --> 01:11:07,300 So what I'll do is I'll find problems that can be solved 1586 01:11:07,300 --> 01:11:08,550 multiple ways. 1587 01:11:12,190 --> 01:11:15,130 Suppose this is, for example, a problem about a pendulum. 1588 01:11:15,130 --> 01:11:17,670 Well, you can solve a pendulum with dimensional analysis. 1589 01:11:17,670 --> 01:11:21,540 You can also solve a pendulum with conservation laws. 1590 01:11:21,540 --> 01:11:22,740 So I'll do it again. 1591 01:11:22,740 --> 01:11:26,060 So this way, this method is sufficient to solve it mostly. 1592 01:11:26,060 --> 01:11:27,550 This method is sufficient, but now we're 1593 01:11:27,550 --> 01:11:29,970 revisiting the old problem. 1594 01:11:29,970 --> 01:11:35,610 So I try to find problems that thread through, and maybe then 1595 01:11:35,610 --> 01:11:37,180 reappear over here. 1596 01:11:37,180 --> 01:11:41,440 So that gives you a cross cutting organization. 1597 01:11:41,440 --> 01:11:44,650 So you can do that not just with problems, but with, for 1598 01:11:44,650 --> 01:11:46,380 example, other principles. 1599 01:11:46,380 --> 01:11:48,160 For example, the history-- 1600 01:11:48,160 --> 01:11:51,140 suppose you want to incorporate history versus 1601 01:11:51,140 --> 01:11:52,560 current understanding. 1602 01:11:52,560 --> 01:11:55,170 Well, every time you mention history and the importance of 1603 01:11:55,170 --> 01:11:58,110 history, you say, oh look, there's yet another example 1604 01:11:58,110 --> 01:11:59,050 where we learned from history. 1605 01:11:59,050 --> 01:11:59,990 We learned it here. 1606 01:11:59,990 --> 01:12:01,180 We've learned it in this unit. 1607 01:12:01,180 --> 01:12:05,680 So now the students have yet another structure to bind the 1608 01:12:05,680 --> 01:12:08,640 course together. 1609 01:12:08,640 --> 01:12:11,470 This is hard to do the first time you teach the course. 1610 01:12:11,470 --> 01:12:14,100 What you'll do is this first time you teach your course, 1611 01:12:14,100 --> 01:12:15,460 well, you'll probably do it the regular way. 1612 01:12:15,460 --> 01:12:17,950 The second time, you'll maybe reorganize it this way. 1613 01:12:17,950 --> 01:12:21,020 And the third time you do it, you start building all the 1614 01:12:21,020 --> 01:12:21,970 bridges across it. 1615 01:12:21,970 --> 01:12:24,250 Because that's the only time you actually see them too. 1616 01:12:31,660 --> 01:12:33,970 What are my thoughts on grade inflation? 1617 01:12:33,970 --> 01:12:36,980 I wish every grade was an A. So I think there isn't enough 1618 01:12:36,980 --> 01:12:40,080 of it, because of the studies I said before. 1619 01:12:40,080 --> 01:12:42,850 So I'll talk about that in the penultimate lecture. 1620 01:12:51,730 --> 01:12:55,990 I think most of these, yeah, I think I've now answered with 1621 01:12:55,990 --> 01:12:57,600 other comments or questions that are there, except for 1622 01:12:57,600 --> 01:12:59,060 one, which I'll save for next time.