1 01:00:00,000 --> 01:00:12,791 [MUSIC] 2 01:00:18,791 --> 01:00:21,250 Hello. Welcome back to another episode of 3 01:00:21,333 --> 01:00:22,250 Undercooled and 4 01:00:22,250 --> 01:00:23,833 Materials Education podcast. 5 01:00:25,125 --> 01:00:26,291 Today, Tim and I are going 6 01:00:26,291 --> 01:00:27,541 to talk about demonstrations, 7 01:00:29,125 --> 01:00:31,916 mostly because this was Tim's life for 8 01:00:31,916 --> 01:00:33,666 quite some time before 9 01:00:33,666 --> 01:00:35,125 he became a lecturer. 10 01:00:35,833 --> 01:00:36,250 Sure was. 11 01:00:37,250 --> 01:00:40,083 Let's start with having Tim tell you what 12 01:00:40,083 --> 01:00:41,875 he used to do. Go ahead, Tim. 13 01:00:42,500 --> 01:00:46,291 Sure. Once upon a time when I started at 14 01:00:46,291 --> 01:00:48,333 MSE, my first job in MSE 15 01:00:48,333 --> 01:00:50,833 was being the support guy. 16 01:00:51,208 --> 01:00:53,250 So part of that was helping out with lab 17 01:00:53,250 --> 01:00:55,083 classes. But another big part of it was 18 01:00:55,750 --> 01:00:57,958 developing and implementing the classroom 19 01:00:57,958 --> 01:01:00,708 demos for mostly for our intro classes, 20 01:01:00,708 --> 01:01:03,666 a couple advanced classes as well. So it 21 01:01:03,666 --> 01:01:05,166 was a great learning experience for me. 22 01:01:05,166 --> 01:01:07,250 Hey, what is all this stuff? It was a 23 01:01:07,250 --> 01:01:09,416 good way to get into the field. But 24 01:01:09,416 --> 01:01:11,208 working with different 25 01:01:11,208 --> 01:01:13,833 faculty to come up with ideas for demos 26 01:01:13,833 --> 01:01:14,708 that they wanted to do in 27 01:01:14,708 --> 01:01:16,291 their classes, then trying to help 28 01:01:16,291 --> 01:01:18,958 make those real was a really interesting 29 01:01:18,958 --> 01:01:21,625 bit of work that I did and 30 01:01:21,625 --> 01:01:22,791 something I would definitely 31 01:01:22,875 --> 01:01:25,291 recommend to anyone who wants to figure 32 01:01:25,291 --> 01:01:26,500 out a little bit more 33 01:01:26,500 --> 01:01:27,416 on the teaching side. 34 01:01:29,000 --> 01:01:32,416 Great. So why demos? What do you think 35 01:01:32,416 --> 01:01:34,375 the value of the demonstration is? 36 01:01:36,500 --> 01:01:39,666 You know, I could see three main 37 01:01:39,666 --> 01:01:42,000 arguments in favor of having classroom 38 01:01:42,000 --> 01:01:43,541 demos. One of them is 39 01:01:43,541 --> 01:01:46,625 engagement. They're fun. That's in its 40 01:01:46,625 --> 01:01:47,500 own right. There is some 41 01:01:47,500 --> 01:01:49,750 value to that. That's not going to 42 01:01:50,416 --> 01:01:53,041 be enough by itself. But sometimes you 43 01:01:53,041 --> 01:01:54,000 just want to say, hey, 44 01:01:54,000 --> 01:01:54,958 let's do something different and 45 01:01:54,958 --> 01:01:57,208 interesting to bring the students back to 46 01:01:57,208 --> 01:01:58,041 life a little bit. So 47 01:01:58,041 --> 01:02:00,041 that's fine. And for that, almost 48 01:02:00,083 --> 01:02:02,666 anything works. The second aspect and the 49 01:02:02,666 --> 01:02:03,916 one that I'd argue is the 50 01:02:03,916 --> 01:02:05,500 most important out of these three 51 01:02:05,833 --> 01:02:08,583 is the fact that you can have students 52 01:02:08,583 --> 01:02:12,708 make and test predictions in 53 01:02:12,708 --> 01:02:14,291 real time live while they're 54 01:02:14,333 --> 01:02:17,208 learning the content and to have a much 55 01:02:17,208 --> 01:02:20,750 faster, much faster 56 01:02:20,750 --> 01:02:22,791 feedback response than what you get 57 01:02:22,791 --> 01:02:24,333 in a real lab when you're doing 58 01:02:24,333 --> 01:02:25,500 experiments or when you're doing 59 01:02:25,500 --> 01:02:27,041 simulations. You know, that can be a 60 01:02:27,333 --> 01:02:29,541 year's effort to find out whether your 61 01:02:29,541 --> 01:02:30,500 prediction was correct. 62 01:02:31,000 --> 01:02:32,000 So to find out in minutes, 63 01:02:32,541 --> 01:02:34,250 do I understand this? Am I thinking about 64 01:02:34,250 --> 01:02:35,750 it correctly? That's very powerful. 65 01:02:36,625 --> 01:02:41,458 And then the third aspect is that demos 66 01:02:41,458 --> 01:02:44,375 can be used as a launching point for a 67 01:02:44,375 --> 01:02:45,708 further investigation 68 01:02:45,708 --> 01:02:48,291 on the student side. So that can be a way 69 01:02:48,291 --> 01:02:50,208 to develop into an out of 70 01:02:50,208 --> 01:02:51,166 class assignment, like a 71 01:02:51,166 --> 01:02:54,291 homework, for example. And that can be a 72 01:02:54,291 --> 01:02:56,291 nice way to say, okay, we're learning 73 01:02:56,291 --> 01:02:57,125 this stuff in class, 74 01:02:57,625 --> 01:02:59,500 but now go out and connect it to the rest 75 01:02:59,500 --> 01:03:02,125 of the world. That's 76 01:03:02,125 --> 01:03:03,666 pretty good. So of course, 77 01:03:03,833 --> 01:03:05,833 I've been teaching intro to materials for 78 01:03:05,833 --> 01:03:07,958 a very long time, and I 79 01:03:07,958 --> 01:03:09,125 don't think I could do it without 80 01:03:09,166 --> 01:03:11,750 doing demonstrations. Otherwise, it's 81 01:03:11,750 --> 01:03:13,166 just us talking, you know, 82 01:03:13,166 --> 01:03:14,208 yap, yap, yap in front of the 83 01:03:14,208 --> 01:03:15,916 class, and they don't really believe that 84 01:03:15,916 --> 01:03:16,958 anything I'm saying is 85 01:03:16,958 --> 01:03:20,541 true. So at least the demos show 86 01:03:20,625 --> 01:03:23,125 that there's some real life thing going 87 01:03:23,125 --> 01:03:26,875 on. And I tend to far 88 01:03:26,875 --> 01:03:28,666 prefer physical demonstrations 89 01:03:29,458 --> 01:03:31,791 to all the virtual demonstrations that 90 01:03:31,791 --> 01:03:34,541 have been coming up. I've 91 01:03:34,541 --> 01:03:36,958 seen a lot of them. And I, 92 01:03:37,333 --> 01:03:39,541 you know, in my opinion, I just don't get 93 01:03:39,541 --> 01:03:42,541 it. They seem like very black box 94 01:03:42,541 --> 01:03:44,125 modules, where you have 95 01:03:44,125 --> 01:03:46,208 little sliders to change parameters, and 96 01:03:46,208 --> 01:03:47,125 you just look how the math 97 01:03:47,125 --> 01:03:49,500 changes. And that just kind of 98 01:03:49,500 --> 01:03:52,125 leaves me kind of flat. And there's no 99 01:03:52,125 --> 01:03:53,166 connection to the real 100 01:03:53,166 --> 01:03:55,125 physical world when you do that. 101 01:03:55,708 --> 01:03:57,416 Whereas when you try a real physical 102 01:03:57,416 --> 01:03:59,125 demo, you know, you eat 103 01:03:59,125 --> 01:04:01,375 something up, you stretch something, 104 01:04:01,375 --> 01:04:04,000 you bang on it, you do something to it, 105 01:04:04,416 --> 01:04:05,541 you actually see it 106 01:04:05,541 --> 01:04:08,041 respond. And it's hard to deny 107 01:04:08,041 --> 01:04:09,666 that that's a real thing that just 108 01:04:09,666 --> 01:04:13,708 happened. And so to me, physical 109 01:04:13,708 --> 01:04:16,666 demonstrations are so powerful, 110 01:04:17,000 --> 01:04:19,208 besides all the three things you just 111 01:04:19,208 --> 01:04:20,958 mentioned, I think they're 112 01:04:20,958 --> 01:04:22,458 just powerful because they 113 01:04:22,541 --> 01:04:27,291 expand a student's everyday experience. 114 01:04:28,083 --> 01:04:29,208 And I don't think everyday 115 01:04:29,208 --> 01:04:32,291 experience should ever be 116 01:04:32,291 --> 01:04:34,791 discounted. It's what we are, you know, 117 01:04:34,791 --> 01:04:37,208 we grow up, we fall down and 118 01:04:37,208 --> 01:04:39,083 it hurts, we run into a wall and 119 01:04:39,083 --> 01:04:42,291 it hurts. And it's a real thing to 120 01:04:42,291 --> 01:04:45,250 anybody who's experienced any of those 121 01:04:45,250 --> 01:04:47,500 things. And unfortunately, 122 01:04:48,000 --> 01:04:50,666 everyday experience doesn't always serve 123 01:04:50,666 --> 01:04:53,000 us well. And that's kind of our job as 124 01:04:53,000 --> 01:04:54,708 educators to explain 125 01:04:54,708 --> 01:04:57,916 to students that, yeah, you know a lot, 126 01:04:58,208 --> 01:04:59,958 and we really value what you 127 01:04:59,958 --> 01:05:01,541 know. But there's a lot you 128 01:05:01,541 --> 01:05:04,375 probably don't know. A lot of things you 129 01:05:04,375 --> 01:05:06,291 haven't quite experienced 130 01:05:06,291 --> 01:05:08,750 that we want to make you aware 131 01:05:08,791 --> 01:05:12,083 of. Because if you can understand these 132 01:05:12,083 --> 01:05:14,416 concepts and these ideas that we're 133 01:05:14,416 --> 01:05:15,458 trying to teach you, 134 01:05:15,833 --> 01:05:18,666 and start to believe it and start to fold 135 01:05:18,666 --> 01:05:19,833 it into your everyday 136 01:05:19,833 --> 01:05:21,958 experience, you're going to develop 137 01:05:21,958 --> 01:05:25,333 a really high quality intuition that will 138 01:05:25,333 --> 01:05:27,958 help you design things using the 139 01:05:27,958 --> 01:05:29,500 fundamentals of material 140 01:05:29,500 --> 01:05:32,291 science. It's kind of what we do. And so 141 01:05:32,291 --> 01:05:33,833 doing demonstrations, I 142 01:05:33,833 --> 01:05:35,541 think is just a critical part 143 01:05:35,833 --> 01:05:40,500 of teaching material science. So at least 144 01:05:40,500 --> 01:05:42,416 that's how I feel. I 145 01:05:42,416 --> 01:05:44,125 never cared much for these, 146 01:05:45,041 --> 01:05:47,750 the physics FET demonstrations or 147 01:05:47,750 --> 01:05:49,791 JavaScript things because, 148 01:05:50,125 --> 01:05:53,458 yeah, they're kind of cool, but 149 01:05:54,291 --> 01:05:57,583 they illustrate certain things, but they 150 01:05:57,583 --> 01:05:58,916 don't really add to that 151 01:05:58,916 --> 01:06:01,583 individual experience. And I 152 01:06:01,583 --> 01:06:05,375 think that's really special. Yeah, I 153 01:06:05,375 --> 01:06:08,000 definitely have to agree on how important 154 01:06:08,000 --> 01:06:09,125 students' individual 155 01:06:09,125 --> 01:06:11,333 experiences are, both what they bring to 156 01:06:11,333 --> 01:06:12,583 the class as well as what 157 01:06:12,583 --> 01:06:13,750 they experience in class. 158 01:06:14,000 --> 01:06:16,166 And this is where the right demo at the 159 01:06:16,166 --> 01:06:17,083 right time can be so 160 01:06:17,083 --> 01:06:19,500 powerful because of students from 161 01:06:19,500 --> 01:06:21,041 their everyday life and from their prior 162 01:06:21,041 --> 01:06:23,208 experience, if they have one expectation 163 01:06:23,208 --> 01:06:24,250 about how a material 164 01:06:24,333 --> 01:06:27,416 should behave and then they see it in 165 01:06:27,416 --> 01:06:29,666 real time live in front of their eyes 166 01:06:29,666 --> 01:06:30,833 behaving in a different 167 01:06:30,833 --> 01:06:32,750 way, that's not what they expected. That 168 01:06:32,750 --> 01:06:33,666 can be a really powerful 169 01:06:33,666 --> 01:06:35,083 catalyst to get them to 170 01:06:35,500 --> 01:06:37,458 evaluate how they understand the content 171 01:06:37,458 --> 01:06:38,208 that we're trying to teach. 172 01:06:39,208 --> 01:06:42,958 Right. Now, of course, the kind of demo 173 01:06:42,958 --> 01:06:44,208 that you would choose 174 01:06:44,208 --> 01:06:47,083 depends pretty much entirely on who 175 01:06:47,083 --> 01:06:50,541 the audience is. So, you know, we've kind 176 01:06:50,541 --> 01:06:52,833 of just been talking about 177 01:06:52,833 --> 01:06:54,708 intro to materials courses, 178 01:06:55,583 --> 01:06:57,375 because that's what you and I do the most 179 01:06:57,375 --> 01:06:59,625 of the time. But there's a 180 01:06:59,625 --> 01:07:01,500 lot of other audiences that 181 01:07:01,500 --> 01:07:06,000 I think you have to tune the demo to the 182 01:07:06,000 --> 01:07:07,833 audience to make sure they'll 183 01:07:07,833 --> 01:07:09,291 be able to receive it and get 184 01:07:09,291 --> 01:07:11,166 something out of it. You know, for 185 01:07:11,166 --> 01:07:14,416 instance, when you go into a K through 186 01:07:14,416 --> 01:07:16,041 six class doing outreach, 187 01:07:16,708 --> 01:07:18,958 you're probably not going to show them 188 01:07:18,958 --> 01:07:21,125 the zinc aluminum system 189 01:07:21,125 --> 01:07:22,541 where you get this metastable 190 01:07:22,541 --> 01:07:24,916 state and you smack it and it gets hot. 191 01:07:25,375 --> 01:07:26,708 They would have no chance 192 01:07:26,708 --> 01:07:28,125 of really understanding that. 193 01:07:29,041 --> 01:07:31,916 On the other hand, liquid nitrogen ice 194 01:07:31,916 --> 01:07:35,083 cream. Wow. That's a fun 195 01:07:35,083 --> 01:07:38,083 thing for little kids to do. And 196 01:07:38,083 --> 01:07:40,083 it connects with their everyday 197 01:07:40,083 --> 01:07:43,333 experience with eating ice cream. And now 198 01:07:43,333 --> 01:07:44,291 you can talk to them 199 01:07:44,291 --> 01:07:47,041 about how you can change the texture of 200 01:07:47,041 --> 01:07:48,708 that ice cream by changing 201 01:07:48,708 --> 01:07:50,333 the kinetics of that experiment, 202 01:07:50,791 --> 01:07:53,000 which is kind of cool. I love that 203 01:07:53,000 --> 01:07:54,250 example, because that is 204 01:07:54,250 --> 01:07:55,666 one that really does work at 205 01:07:56,083 --> 01:07:58,666 all levels exactly as you described, even 206 01:07:58,666 --> 01:08:00,541 for a young child, it's 207 01:08:00,541 --> 01:08:02,041 ice cream. But then that can 208 01:08:02,041 --> 01:08:04,250 go all the way up to an undergraduate or 209 01:08:04,250 --> 01:08:05,333 even a graduate kinetics 210 01:08:05,333 --> 01:08:06,541 course where you're looking at 211 01:08:06,875 --> 01:08:08,750 the nucleation and growth of ice crystals 212 01:08:08,750 --> 01:08:10,750 and how this is affected by 213 01:08:10,750 --> 01:08:13,458 the cooling rate and by the 214 01:08:13,666 --> 01:08:16,125 ratio of, you know, nitrogen to cream and 215 01:08:16,125 --> 01:08:17,708 these other factors, it can 216 01:08:17,708 --> 01:08:20,500 become very complex or not 217 01:08:20,500 --> 01:08:22,083 as you want it to be. And that's 218 01:08:22,083 --> 01:08:23,833 something that I think we should try to 219 01:08:23,833 --> 01:08:24,708 aim for with all of our 220 01:08:24,750 --> 01:08:26,375 demos is that they really do work at 221 01:08:26,375 --> 01:08:28,041 multiple levels so that 222 01:08:28,041 --> 01:08:29,541 we're not trying to create 223 01:08:29,583 --> 01:08:31,666 entirely new suites of content for every 224 01:08:31,666 --> 01:08:34,125 separate audience. And that's 225 01:08:34,125 --> 01:08:35,666 great if we can pull it off, 226 01:08:35,666 --> 01:08:38,041 but sometimes it's hard. You know, so 227 01:08:38,041 --> 01:08:41,625 like a silly putty. Yeah, we do use that 228 01:08:41,625 --> 01:08:43,291 to show viscoelastic 229 01:08:43,291 --> 01:08:46,250 behavior at any level, but it's a really 230 01:08:46,250 --> 01:08:47,875 simple concept, at least the 231 01:08:47,875 --> 01:08:50,125 silly putty part. So that's 232 01:08:50,166 --> 01:08:52,958 more amenable to K through six or high 233 01:08:52,958 --> 01:08:54,083 school students, even 234 01:08:54,083 --> 01:08:56,333 intro material students. But I 235 01:08:56,333 --> 01:08:57,583 don't think we want to be pulling out 236 01:08:57,583 --> 01:09:00,208 silly putty for a graduate course and 237 01:09:00,208 --> 01:09:01,291 polymers. I think they 238 01:09:01,291 --> 01:09:04,875 know that. But the other kinds of demos 239 01:09:04,875 --> 01:09:08,083 that we do all the time, a lot of us go 240 01:09:08,083 --> 01:09:09,125 into high schools to 241 01:09:09,125 --> 01:09:10,958 try to get students excited about 242 01:09:10,958 --> 01:09:14,041 material science so that they might 243 01:09:14,041 --> 01:09:15,833 choose a materials career. 244 01:09:16,500 --> 01:09:18,583 And so I know you've done a lot of this. 245 01:09:18,583 --> 01:09:21,208 I've done some. And I think the most 246 01:09:21,208 --> 01:09:22,500 exciting tool that we 247 01:09:22,500 --> 01:09:26,875 can bring to high schools is the portable 248 01:09:26,875 --> 01:09:28,291 scanning electron 249 01:09:28,291 --> 01:09:30,791 microscopes. Maybe you can talk a little 250 01:09:30,791 --> 01:09:34,750 bit about how we do that. Sure. The 251 01:09:34,750 --> 01:09:37,041 future is an amazing place. You can just 252 01:09:37,041 --> 01:09:38,250 take an SEM and carry 253 01:09:38,250 --> 01:09:39,916 it around in the back of your car now. 254 01:09:40,916 --> 01:09:44,500 And there are tabletop models made by a 255 01:09:44,500 --> 01:09:45,625 variety of manufacturers 256 01:09:45,791 --> 01:09:50,500 now that we've taken to classrooms, to 257 01:09:50,500 --> 01:09:52,333 museums, to public 258 01:09:52,333 --> 01:09:54,416 science centers even. And 259 01:09:55,666 --> 01:09:58,083 you know, the power of that, this will 260 01:09:58,083 --> 01:09:59,375 also connect back to your point about 261 01:09:59,375 --> 01:10:00,500 virtual demos, I think. 262 01:10:01,083 --> 01:10:02,541 One of the things that really makes 263 01:10:02,541 --> 01:10:04,375 materials science special 264 01:10:04,375 --> 01:10:06,083 is how we work across so many 265 01:10:06,083 --> 01:10:08,708 length scales. And to be able to zoom in 266 01:10:08,708 --> 01:10:11,208 real time from 10x to 100 267 01:10:11,208 --> 01:10:14,125 to 1000 to 10,000 to 50,000, 268 01:10:14,500 --> 01:10:16,750 and to see a single object at so many 269 01:10:16,750 --> 01:10:17,708 different length scales 270 01:10:17,708 --> 01:10:19,541 can really be a mind-blowing 271 01:10:19,541 --> 01:10:22,000 experience and get people to think, "I 272 01:10:22,000 --> 01:10:22,791 didn't even know that 273 01:10:22,791 --> 01:10:26,166 existed." So I am very glad that 274 01:10:26,458 --> 01:10:28,916 we have the ability technologically to do 275 01:10:28,916 --> 01:10:30,791 that now and to bring that to people 276 01:10:30,958 --> 01:10:32,291 instead of having to wait until they're 277 01:10:32,291 --> 01:10:33,541 already in the university. 278 01:10:36,166 --> 01:10:38,416 Especially when you show them things like 279 01:10:38,416 --> 01:10:39,791 shark skin, because they 280 01:10:39,791 --> 01:10:41,791 hear about the Olympics and 281 01:10:42,250 --> 01:10:44,458 athletes wearing these shark skin bathing 282 01:10:44,458 --> 01:10:46,583 suits for swimming, which 283 01:10:46,583 --> 01:10:47,666 are outlawed now because they 284 01:10:47,666 --> 01:10:51,041 work too well. But to show them what 285 01:10:51,041 --> 01:10:52,083 shark skin actually 286 01:10:52,083 --> 01:10:53,833 looks like, to show them how 287 01:10:53,916 --> 01:10:56,000 butterfly wings are really diffraction 288 01:10:56,000 --> 01:10:57,125 gratings, and that's why 289 01:10:57,125 --> 01:10:59,000 you get all those weird colors 290 01:10:59,458 --> 01:11:02,833 off the wings when they shimmer. Even 291 01:11:02,833 --> 01:11:06,375 just showing them the width of Lincoln's 292 01:11:06,375 --> 01:11:07,833 leg on a Lincoln penny, 293 01:11:08,583 --> 01:11:12,291 because his leg is 100 microns wide, and 294 01:11:12,291 --> 01:11:13,625 you can just barely see 295 01:11:13,625 --> 01:11:15,791 that on the penny with your 296 01:11:15,791 --> 01:11:18,541 naked eye, but you can really see it in 297 01:11:18,541 --> 01:11:21,750 the SEM. And it just gives a way to 298 01:11:21,750 --> 01:11:24,291 connect with real life 299 01:11:24,541 --> 01:11:26,875 at all these different length scales. And 300 01:11:26,875 --> 01:11:28,958 I think that's really 301 01:11:28,958 --> 01:11:30,500 important for high school kids, 302 01:11:30,500 --> 01:11:32,250 because they haven't really appreciated 303 01:11:32,250 --> 01:11:34,750 that yet. Whereas college 304 01:11:34,750 --> 01:11:36,083 kids and certainly graduate 305 01:11:36,250 --> 01:11:38,666 students, they have. They understand all 306 01:11:38,666 --> 01:11:41,166 that. But you can use the 307 01:11:41,166 --> 01:11:43,791 same tool to do other things 308 01:11:44,291 --> 01:11:46,958 for the graduate students, looking at 309 01:11:46,958 --> 01:11:48,833 twinning and all this other neat stuff. 310 01:11:50,500 --> 01:11:53,000 And then the other place we use 311 01:11:53,000 --> 01:11:57,083 demonstrations is when we go to career 312 01:11:57,083 --> 01:12:00,208 fairs or majors fairs, 313 01:12:00,208 --> 01:12:02,708 where we bring things to try to get 314 01:12:02,708 --> 01:12:03,666 people to come to our 315 01:12:03,666 --> 01:12:05,416 table to come to talk to us. 316 01:12:05,708 --> 01:12:08,083 So we have a shot at convincing them how 317 01:12:08,083 --> 01:12:09,166 cool material science 318 01:12:09,166 --> 01:12:11,000 is. And those are a little 319 01:12:11,041 --> 01:12:15,083 different. I mean, I think the demo I've 320 01:12:15,083 --> 01:12:16,583 always liked the most is 321 01:12:16,583 --> 01:12:18,291 the one with the CD that you 322 01:12:18,291 --> 01:12:20,583 squish in there, you spray that stuff, it 323 01:12:20,583 --> 01:12:23,125 slams out. Things that 324 01:12:23,125 --> 01:12:25,750 blow up or explode really get 325 01:12:25,958 --> 01:12:28,833 the students excited. Maybe as soon as 326 01:12:28,833 --> 01:12:30,833 there's a crowd, a crowd of 327 01:12:30,833 --> 01:12:32,291 people with everyone wearing 328 01:12:32,333 --> 01:12:34,500 safety glasses and loud noises happening, 329 01:12:34,875 --> 01:12:36,375 and the whole room wants to 330 01:12:36,375 --> 01:12:37,166 know, well, what's happening 331 01:12:37,166 --> 01:12:38,708 over there? That must be the cool kids 332 01:12:38,708 --> 01:12:41,875 table. So it can certainly be 333 01:12:41,875 --> 01:12:43,083 a good way to rope people in. 334 01:12:43,750 --> 01:12:48,333 That particular demo, how it works is you 335 01:12:48,333 --> 01:12:49,791 have to acquire these 336 01:12:49,791 --> 01:12:51,750 legendary artifacts known as 337 01:12:51,750 --> 01:12:53,833 compact discs, they come from a previous 338 01:12:53,833 --> 01:12:56,166 age. And if you can get 339 01:12:56,166 --> 01:12:58,125 enough of them in one place, 340 01:12:58,791 --> 01:13:04,000 what you do is you put the CD under some 341 01:13:04,000 --> 01:13:05,625 flexural stress. So have a 342 01:13:05,625 --> 01:13:06,875 mount that you can clamp it into 343 01:13:06,875 --> 01:13:10,708 and squeeze it a little bit and spray it 344 01:13:10,708 --> 01:13:12,041 with furniture polish. 345 01:13:13,666 --> 01:13:16,375 And what will happen is that 346 01:13:16,375 --> 01:13:19,500 the furniture polish will change the 347 01:13:19,500 --> 01:13:21,833 cross linking between the 348 01:13:21,833 --> 01:13:23,916 polycarbonate chains in the CD, 349 01:13:24,541 --> 01:13:30,375 and it will reach the point where the 350 01:13:30,375 --> 01:13:33,041 strength of the polycarbonate 351 01:13:33,041 --> 01:13:34,916 changes, but it's still held 352 01:13:34,916 --> 01:13:36,500 under this constant stress and eventually 353 01:13:36,500 --> 01:13:38,291 it fails. And so the CD 354 01:13:38,291 --> 01:13:41,208 will snap and jump out of 355 01:13:41,208 --> 01:13:44,083 the holder into usually a few pieces. And 356 01:13:44,083 --> 01:13:46,916 it's a really great way 357 01:13:46,916 --> 01:13:48,416 to illustrate that chemical 358 01:13:48,666 --> 01:13:51,250 stresses and chemical processing of 359 01:13:51,250 --> 01:13:54,666 materials alongside mechanical stresses 360 01:13:54,666 --> 01:13:55,916 are really important 361 01:13:55,916 --> 01:13:57,875 to understanding processing and materials 362 01:13:57,875 --> 01:14:00,583 properties. Yep, 363 01:14:00,583 --> 01:14:02,333 that's a cool one. And then 364 01:14:02,333 --> 01:14:06,375 finally, another really important kind of 365 01:14:06,375 --> 01:14:08,333 demonstration for the materials community 366 01:14:08,541 --> 01:14:10,416 is what we do with our teachers camps. 367 01:14:11,041 --> 01:14:12,250 And you've been involved with the 368 01:14:12,250 --> 01:14:13,333 teachers camps for years, 369 01:14:13,375 --> 01:14:16,500 Tim, and maybe you can talk about, they 370 01:14:16,500 --> 01:14:18,000 have a different set of 371 01:14:18,000 --> 01:14:19,500 boundary conditions, right? 372 01:14:19,500 --> 01:14:21,708 Things have to be cheap and they have to 373 01:14:21,708 --> 01:14:23,916 fit into lesson plans. And 374 01:14:23,916 --> 01:14:25,625 that's been pretty much the 375 01:14:25,916 --> 01:14:29,375 hallmark of the whole ASM Foundation 376 01:14:29,375 --> 01:14:31,833 teachers camps is showing 377 01:14:31,833 --> 01:14:34,166 these teachers how to do these 378 01:14:34,166 --> 01:14:36,791 demonstrations in class as part of the 379 01:14:36,791 --> 01:14:39,250 curriculum. And so maybe you can describe 380 01:14:39,250 --> 01:14:40,208 some of those for us. 381 01:14:41,416 --> 01:14:45,166 Yeah, the ASM teachers camp, anyone out 382 01:14:45,166 --> 01:14:46,750 there who's listening to 383 01:14:46,750 --> 01:14:48,958 this, if there is one in your area 384 01:14:48,958 --> 01:14:51,250 and you haven't interacted with it, I 385 01:14:51,250 --> 01:14:52,500 would absolutely recommend 386 01:14:52,500 --> 01:14:53,958 that. It's a great experience. 387 01:14:54,625 --> 01:14:57,166 It is a good way to build relationships 388 01:14:57,166 --> 01:14:59,125 within your community as 389 01:14:59,125 --> 01:15:00,750 well. And also a good way to 390 01:15:00,750 --> 01:15:03,166 pick up some good tips for your own MSE 391 01:15:03,166 --> 01:15:04,875 classes. Here's a couple 392 01:15:04,875 --> 01:15:07,083 examples. Many of them are quite 393 01:15:07,208 --> 01:15:10,416 chemistry oriented. A lot of the schools 394 01:15:10,416 --> 01:15:11,958 where these teachers are 395 01:15:11,958 --> 01:15:14,000 teaching don't have a material 396 01:15:14,000 --> 01:15:16,000 science class. They might have a 397 01:15:16,000 --> 01:15:19,250 "engineering course." Some 398 01:15:19,250 --> 01:15:20,708 have physics classes, but mostly 399 01:15:20,708 --> 01:15:22,416 they're teaching chemistry. And so 400 01:15:22,416 --> 01:15:24,250 they're approaching really material 401 01:15:24,250 --> 01:15:25,583 science from the view 402 01:15:25,666 --> 01:15:28,125 of what can a high school chemistry 403 01:15:28,125 --> 01:15:31,250 student engage with. So they're looking 404 01:15:31,250 --> 01:15:33,166 at crystal growth and 405 01:15:33,208 --> 01:15:36,625 single replacement reactions. For 406 01:15:36,625 --> 01:15:40,166 example, there is a demo that they do 407 01:15:40,166 --> 01:15:42,208 where students take a 408 01:15:42,208 --> 01:15:45,750 galvanized nail. They immerse it in a 409 01:15:45,750 --> 01:15:49,333 copper, I believe it's a 410 01:15:49,333 --> 01:15:52,000 copper chloride solution, and they 411 01:15:52,000 --> 01:15:55,750 grow metallic copper off of this nail as 412 01:15:55,750 --> 01:15:58,666 the copper replaces the zinc atoms on the 413 01:15:58,666 --> 01:15:59,333 surface of the nail. 414 01:15:59,916 --> 01:16:04,583 So that's a really great one. And another 415 01:16:04,583 --> 01:16:07,833 example that we use all the 416 01:16:07,833 --> 01:16:09,666 time at the college level as 417 01:16:10,333 --> 01:16:13,208 college level is the iron wire. It's 418 01:16:13,208 --> 01:16:16,375 truly one of the classic greats of MSE 419 01:16:16,375 --> 01:16:17,708 demos, I feel. And Steve, 420 01:16:17,708 --> 01:16:19,666 I know you use the iron wire in your 421 01:16:19,666 --> 01:16:21,791 classes as well. So can 422 01:16:21,791 --> 01:16:22,833 you talk us through that one? 423 01:16:23,583 --> 01:16:25,208 Yeah, I love that one. This is of course 424 01:16:25,208 --> 01:16:27,416 where you take a piano 425 01:16:27,416 --> 01:16:28,375 wire, which is a very, 426 01:16:28,416 --> 01:16:31,625 very low carbon steel, almost zero 427 01:16:31,625 --> 01:16:34,333 percent carbon, and you stretch it out 428 01:16:34,333 --> 01:16:36,500 and you do something you 429 01:16:36,500 --> 01:16:38,500 tell the kids, "Don't do this at home." 430 01:16:38,833 --> 01:16:40,416 And you take the two ends 431 01:16:40,416 --> 01:16:42,375 and you plug it into a variac 432 01:16:43,000 --> 01:16:47,291 and you just crank it up. And as the wire 433 01:16:47,291 --> 01:16:48,458 gets hotter and higher, 434 01:16:48,708 --> 01:16:49,708 of course you get thermal 435 01:16:49,708 --> 01:16:54,000 expansion. But it's two effects that 436 01:16:54,000 --> 01:16:55,083 you're trying to teach. 437 01:16:55,083 --> 01:16:56,041 One is thermal expansion, 438 01:16:56,166 --> 01:16:59,208 of course the other is the BCC to FCC 439 01:16:59,208 --> 01:17:00,958 phase transformation of 440 01:17:00,958 --> 01:17:03,250 iron. And so as it's heating, 441 01:17:04,083 --> 01:17:06,250 it starts to get hot, red hot, and it's 442 01:17:06,250 --> 01:17:08,791 sagging. But right when it hits the 443 01:17:08,791 --> 01:17:10,833 transition to FCC iron, 444 01:17:11,250 --> 01:17:13,958 because FCC is more close packed than 445 01:17:13,958 --> 01:17:18,250 BCC, it's a volumetric phase 446 01:17:18,250 --> 01:17:20,125 transformation. So it shrinks. 447 01:17:20,500 --> 01:17:23,291 So it goes down, then it goes up, and 448 01:17:23,291 --> 01:17:24,166 then because you're still 449 01:17:24,166 --> 01:17:25,458 heating it, it eventually 450 01:17:25,500 --> 01:17:28,291 expands and goes down. And it's really 451 01:17:28,291 --> 01:17:30,166 obvious when you cool it. 452 01:17:31,041 --> 01:17:32,541 So once it's glowing hot, 453 01:17:32,750 --> 01:17:34,541 all the way down above, it's an 454 01:17:34,541 --> 01:17:37,791 austenitic material, you just turn off 455 01:17:37,791 --> 01:17:40,000 the variac and it comes back up 456 01:17:40,666 --> 01:17:43,000 and then it drops down and then it goes 457 01:17:43,000 --> 01:17:45,375 back up again. And most 458 01:17:45,375 --> 01:17:47,541 students get the thermal expansion 459 01:17:47,833 --> 01:17:52,416 part, but very, very few remember about 460 01:17:52,416 --> 01:17:53,875 the volumetric phase 461 01:17:53,875 --> 01:17:55,333 transformation, because that's 462 01:17:55,333 --> 01:17:57,833 kind of a new concept for most students. 463 01:17:58,000 --> 01:17:59,625 Most students, they come 464 01:17:59,625 --> 01:18:01,541 into college and they've 465 01:18:01,541 --> 01:18:03,708 heard of phase transformations. They know 466 01:18:03,708 --> 01:18:05,666 you can go from liquid to 467 01:18:05,666 --> 01:18:07,833 solid to gas, and that's it. 468 01:18:08,166 --> 01:18:10,250 That's all you learn in high school. And 469 01:18:10,250 --> 01:18:11,916 now we tell them that a 470 01:18:11,916 --> 01:18:13,583 phase can be different 471 01:18:14,083 --> 01:18:17,041 crystal structures. And that is kind of 472 01:18:17,041 --> 01:18:18,500 very disturbing to them 473 01:18:18,500 --> 01:18:20,583 because it's challenging what 474 01:18:20,583 --> 01:18:22,833 they thought they understood. And now we 475 01:18:22,833 --> 01:18:23,791 tell them that there's 476 01:18:23,791 --> 01:18:26,583 more to it. And so what is a 477 01:18:26,583 --> 01:18:28,541 different crystal structure? Well, there 478 01:18:28,541 --> 01:18:30,333 are, you know, you can show them x-ray 479 01:18:30,333 --> 01:18:31,208 diffraction patterns, 480 01:18:31,291 --> 01:18:32,625 but I don't know if they're going to 481 01:18:32,625 --> 01:18:34,791 believe that. But if you show them a 482 01:18:34,791 --> 01:18:36,458 volumetric change and how 483 01:18:36,458 --> 01:18:38,958 it's reversible, it goes up and down. And 484 01:18:38,958 --> 01:18:39,791 then I tell them how when 485 01:18:39,791 --> 01:18:40,833 I was a graduate student, 486 01:18:41,291 --> 01:18:45,041 I used single crystal iron samples that 487 01:18:45,041 --> 01:18:46,333 had to be very expensive 488 01:18:46,333 --> 01:18:47,541 because you can only make them 489 01:18:47,541 --> 01:18:49,458 with something called strain annealing. 490 01:18:49,958 --> 01:18:51,166 So my little tiny sample 491 01:18:51,166 --> 01:18:53,791 was like 800 bucks. And once 492 01:18:53,791 --> 01:18:56,083 I made the mistake when I was sputter 493 01:18:56,083 --> 01:18:57,916 cleaning it, you know, I had 494 01:18:57,916 --> 01:19:00,416 two wires spot welded to it, 495 01:19:00,791 --> 01:19:03,666 right? So I would heat the wires and it 496 01:19:03,666 --> 01:19:05,500 would get hot. Well, I took 497 01:19:05,500 --> 01:19:07,000 it up too high. I took it up 498 01:19:07,041 --> 01:19:10,458 above the BCC and FCC phase 499 01:19:10,458 --> 01:19:13,333 transformation. And yeah, it came back as 500 01:19:13,333 --> 01:19:15,000 BCC, but it wasn't a single 501 01:19:15,000 --> 01:19:18,666 crystal anymore. It was a mess. And my 502 01:19:18,666 --> 01:19:20,625 advisor was very kind to me and said, 503 01:19:20,625 --> 01:19:21,375 don't worry about it. 504 01:19:21,375 --> 01:19:23,833 Just don't do it again. And he bought me 505 01:19:23,833 --> 01:19:26,166 a new one. That's very nice. 506 01:19:26,916 --> 01:19:29,041 But it's, you know, you get, 507 01:19:29,333 --> 01:19:32,083 you know, those of us who do these things 508 01:19:32,083 --> 01:19:33,458 in research, we get burned 509 01:19:33,458 --> 01:19:34,958 all the time by our demos, 510 01:19:35,750 --> 01:19:37,500 which brings up a really interesting 511 01:19:37,500 --> 01:19:40,875 point about demos. You kind of have to 512 01:19:40,875 --> 01:19:41,958 have a sense of humor, 513 01:19:42,333 --> 01:19:45,625 because they don't always work. In fact, 514 01:19:45,833 --> 01:19:49,375 it's very easy to have them not work. 515 01:19:49,625 --> 01:19:51,333 Yes, they will betray you when you need 516 01:19:51,333 --> 01:19:53,708 them the most. Right. And a 517 01:19:53,708 --> 01:19:55,708 lot of that has to do with 518 01:19:56,166 --> 01:19:58,958 the person who sources the materials, 519 01:19:59,458 --> 01:20:01,500 puts it together, trains 520 01:20:01,500 --> 01:20:02,791 the graduate student that's 521 01:20:02,791 --> 01:20:07,083 going to run the demonstration. And often 522 01:20:07,083 --> 01:20:08,458 the only way for that 523 01:20:08,458 --> 01:20:10,250 person, namely you, to really 524 01:20:10,333 --> 01:20:13,208 know that you have a handle on this was 525 01:20:13,208 --> 01:20:14,500 for you to actually come to 526 01:20:14,500 --> 01:20:16,458 class and do the demo yourself. 527 01:20:16,958 --> 01:20:19,458 So you felt extremely comfortable that it 528 01:20:19,458 --> 01:20:20,791 would work. Then you 529 01:20:20,791 --> 01:20:22,541 would be in a position to show 530 01:20:22,541 --> 01:20:25,500 somebody how to do it. For example, the 531 01:20:25,500 --> 01:20:27,708 iron thing, it doesn't always work, 532 01:20:28,000 --> 01:20:29,416 right? And it doesn't 533 01:20:29,458 --> 01:20:32,500 always work. Because if you use one piece 534 01:20:32,500 --> 01:20:34,666 of wire too many times, you 535 01:20:34,666 --> 01:20:35,958 get all these green boundaries 536 01:20:35,958 --> 01:20:37,916 and nano crystalline material, and it 537 01:20:37,916 --> 01:20:40,166 just messes everything up, because those 538 01:20:40,166 --> 01:20:41,416 green boundaries pin 539 01:20:41,583 --> 01:20:44,916 the transformations. And so the trick for 540 01:20:44,916 --> 01:20:46,583 that is to always 541 01:20:46,583 --> 01:20:48,583 start with a fresh wire. 542 01:20:50,875 --> 01:20:52,666 And so, you know, where do you learn 543 01:20:52,666 --> 01:20:54,541 that? Well, by experience, 544 01:20:55,208 --> 01:20:57,291 by doing it a few dozen times and seeing 545 01:20:57,291 --> 01:20:58,333 when it works and when it 546 01:20:58,333 --> 01:21:00,333 doesn't, and finding out what 547 01:21:00,333 --> 01:21:03,166 the stopping points are another one, I 548 01:21:03,166 --> 01:21:04,166 use this to get graduate 549 01:21:04,166 --> 01:21:06,000 students all the time, because 550 01:21:07,375 --> 01:21:10,333 another factor is how quickly you turn up 551 01:21:10,333 --> 01:21:11,458 the temperature on the 552 01:21:11,458 --> 01:21:12,458 wire, because you're feeding 553 01:21:12,458 --> 01:21:14,166 at current, that's your heating mechanism 554 01:21:14,166 --> 01:21:16,250 is dual heating. And the 555 01:21:16,250 --> 01:21:17,375 resistance is a function 556 01:21:17,375 --> 01:21:20,375 of the temperature. But often a novice 557 01:21:20,375 --> 01:21:22,333 implementer of this demo won't be 558 01:21:22,333 --> 01:21:23,166 considering the fact that 559 01:21:23,208 --> 01:21:25,166 the resistance of the wire is changing. 560 01:21:26,416 --> 01:21:27,791 And so they crank up the 561 01:21:27,791 --> 01:21:29,166 current, and then it blows the 562 01:21:29,166 --> 01:21:30,541 fuse in the variac, and then nothing 563 01:21:30,541 --> 01:21:33,541 happens at all. And I did everything 564 01:21:33,541 --> 01:21:34,500 right, what went wrong? 565 01:21:35,375 --> 01:21:38,250 Well, you forgot that the resistance is 566 01:21:38,250 --> 01:21:39,708 lower when it's colder, and 567 01:21:39,708 --> 01:21:41,083 you fed it too much current, 568 01:21:41,125 --> 01:21:43,041 and the fuse couldn't handle it. But if 569 01:21:43,041 --> 01:21:44,333 you ramp it up slowly and let that 570 01:21:44,333 --> 01:21:45,625 resistance go up as well, 571 01:21:45,958 --> 01:21:48,041 then so there are so many little 572 01:21:48,041 --> 01:21:50,083 subtleties like that that, yeah, you 573 01:21:50,083 --> 01:21:51,083 should if you're bringing a 574 01:21:51,125 --> 01:21:54,791 new demo into your class, I would no 575 01:21:54,791 --> 01:21:55,666 kidding recommend 576 01:21:55,666 --> 01:21:57,750 practicing at least a dozen times 577 01:21:57,875 --> 01:21:59,708 before doing it in front of the students 578 01:21:59,708 --> 01:22:00,458 if you want to have a 579 01:22:00,458 --> 01:22:01,291 good chance of success. 580 01:22:01,916 --> 01:22:03,583 If you want to model is how to handle 581 01:22:03,583 --> 01:22:05,625 things going wrong, oh, yeah, jump right 582 01:22:05,625 --> 01:22:06,958 in and give it a go, 583 01:22:06,958 --> 01:22:08,541 something will go wrong for sure. But 584 01:22:08,541 --> 01:22:10,333 usually we want more than that. 585 01:22:11,500 --> 01:22:13,416 Another favorite demo when you want to 586 01:22:13,416 --> 01:22:14,916 show strengthening of 587 01:22:14,916 --> 01:22:17,500 metals, you take a pretty much 588 01:22:17,541 --> 01:22:21,250 pure aluminum bar, and you anneal it. And 589 01:22:21,250 --> 01:22:22,208 then when you anneal it 590 01:22:22,208 --> 01:22:23,958 pure aluminum is very soft, 591 01:22:23,958 --> 01:22:26,708 you can bend that bar very easily. And 592 01:22:26,708 --> 01:22:28,166 then hopefully when you 593 01:22:28,166 --> 01:22:29,500 bend it, you've introduced 594 01:22:29,500 --> 01:22:31,208 enough dislocations that it's very 595 01:22:31,208 --> 01:22:33,791 difficult to bend it back. And so it 596 01:22:33,791 --> 01:22:34,875 sounds great in principle. 597 01:22:35,625 --> 01:22:37,958 But I can't tell you how many times that 598 01:22:37,958 --> 01:22:39,250 demo hasn't worked. 599 01:22:40,083 --> 01:22:42,875 Either the bar wasn't annealed 600 01:22:42,875 --> 01:22:46,375 enough. And I could barely bend it to 601 01:22:46,375 --> 01:22:48,833 begin with. You'd like to do this by 602 01:22:48,833 --> 01:22:50,208 asking someone who thinks 603 01:22:50,500 --> 01:22:53,333 they're really weak, but would like to 604 01:22:53,333 --> 01:22:55,500 demonstrate they can bend metal, they 605 01:22:55,500 --> 01:22:57,083 have them come up. And 606 01:22:57,083 --> 01:22:59,041 if they can't bend it, oh my god, it just 607 01:22:59,041 --> 01:23:01,125 ruins the whole thing. Yeah. 608 01:23:01,875 --> 01:23:05,458 And but the other problem is 609 01:23:05,500 --> 01:23:09,166 if it's too annealed, yeah, it's easy to 610 01:23:09,166 --> 01:23:10,958 bend. But then the strong 611 01:23:10,958 --> 01:23:12,375 people in the class can actually 612 01:23:12,416 --> 01:23:15,250 bend it back. And that again, takes your 613 01:23:15,250 --> 01:23:16,250 thunder away because you 614 01:23:16,250 --> 01:23:17,375 want it. I mean, I'll never 615 01:23:17,375 --> 01:23:19,958 forget. I had one bar that was perfect. 616 01:23:21,041 --> 01:23:22,666 This very weak individual 617 01:23:22,666 --> 01:23:24,625 was able to just bend it. 618 01:23:24,625 --> 01:23:27,791 It made them feel great. And then I said, 619 01:23:27,791 --> 01:23:28,625 anyone think they're a 620 01:23:28,625 --> 01:23:29,916 really big strong guy, 621 01:23:29,916 --> 01:23:32,625 you know, guy or girl, and this Marine 622 01:23:32,625 --> 01:23:36,666 came up. Oh boy. And he 623 01:23:36,666 --> 01:23:38,291 just, he couldn't bend it back. 624 01:23:38,791 --> 01:23:40,541 And I thought he was going to kill me. I 625 01:23:40,541 --> 01:23:41,666 thought he was going to, 626 01:23:41,666 --> 01:23:43,458 because he was so embarrassed 627 01:23:43,458 --> 01:23:45,458 that he couldn't bend back and he was a 628 01:23:45,458 --> 01:23:47,833 Marine. And so I was like a little 629 01:23:47,833 --> 01:23:49,375 fearful, but that was 630 01:23:49,375 --> 01:23:53,000 exactly what you want to happen. So how 631 01:23:53,000 --> 01:23:54,458 do you hit that just right? 632 01:23:54,458 --> 01:23:55,958 And the only way to really do 633 01:23:55,958 --> 01:23:59,166 that is to have enough bars so you can 634 01:23:59,166 --> 01:24:05,000 try one. And so if I've 635 01:24:05,000 --> 01:24:06,166 learned anything about demos, 636 01:24:06,500 --> 01:24:09,083 it's all the things that can go wrong 637 01:24:09,083 --> 01:24:11,708 with a demo and it's going 638 01:24:11,708 --> 01:24:13,125 to happen. And you're just 639 01:24:13,125 --> 01:24:14,583 going to have to explain to the students 640 01:24:14,583 --> 01:24:15,541 that this is real life, 641 01:24:15,541 --> 01:24:16,958 you know, it's complicated 642 01:24:17,291 --> 01:24:19,916 and lots of different things happen. And, 643 01:24:19,916 --> 01:24:23,333 but luckily the 644 01:24:23,333 --> 01:24:26,041 something you said earlier is so 645 01:24:26,250 --> 01:24:30,416 true. What really is important is that 646 01:24:30,416 --> 01:24:32,125 students make a prediction 647 01:24:32,125 --> 01:24:34,958 before you do the demo. And I 648 01:24:35,000 --> 01:24:36,958 believe Eric Mazur has written some 649 01:24:36,958 --> 01:24:39,125 education research papers 650 01:24:39,125 --> 01:24:40,875 demonstrating this and showing 651 01:24:40,958 --> 01:24:44,750 that if the students can predict what's 652 01:24:44,750 --> 01:24:45,875 going to happen before it 653 01:24:45,875 --> 01:24:47,250 happens, it doesn't matter if 654 01:24:47,250 --> 01:24:49,666 they get it right or wrong because 655 01:24:49,666 --> 01:24:52,083 they're roped in. Once they've made a 656 01:24:52,083 --> 01:24:53,458 prediction, they've got 657 01:24:53,458 --> 01:24:55,083 skin in the game. They want to know 658 01:24:55,083 --> 01:24:56,166 what's going to happen. They 659 01:24:56,166 --> 01:24:57,500 want to see if they're right or 660 01:24:57,500 --> 01:25:00,000 wrong. And so they end up paying much 661 01:25:00,000 --> 01:25:01,875 more attention and then 662 01:25:01,875 --> 01:25:03,000 they want to understand why. 663 01:25:03,041 --> 01:25:06,666 And so as long as you can produce a good 664 01:25:06,666 --> 01:25:09,333 reason why, even if the 665 01:25:09,333 --> 01:25:11,583 demo doesn't work, if you can 666 01:25:11,583 --> 01:25:14,166 tell them why it didn't work, they'll 667 01:25:14,166 --> 01:25:16,208 actually learn a lot. And 668 01:25:16,208 --> 01:25:18,625 ultimately our job isn't to make 669 01:25:18,625 --> 01:25:22,541 the demos go great. Sometimes it's good 670 01:25:22,541 --> 01:25:24,375 they see that we fail all the time 671 01:25:24,375 --> 01:25:25,666 because that's normal, 672 01:25:26,041 --> 01:25:29,125 not the other way around. But what really 673 01:25:29,125 --> 01:25:30,208 matters is that they 674 01:25:30,208 --> 01:25:33,166 learn the concept and bring 675 01:25:33,208 --> 01:25:35,541 something into their everyday experience 676 01:25:35,541 --> 01:25:37,166 that they didn't have before 677 01:25:37,166 --> 01:25:39,250 to give them the ability to 678 01:25:39,250 --> 01:25:41,833 think about how more complex things might 679 01:25:41,833 --> 01:25:44,708 happen in the future. I 680 01:25:44,708 --> 01:25:46,583 couldn't agree more. What are 681 01:25:46,583 --> 01:25:48,250 some other greatest hits that we have? 682 01:25:48,250 --> 01:25:51,833 We've talked about a few metals ones. Oh, 683 01:25:51,833 --> 01:25:53,000 a lot of polymer ones. 684 01:25:53,583 --> 01:25:56,416 Yeah. I know one polymer demo that I 685 01:25:56,416 --> 01:25:58,041 really like because it also brings in 686 01:25:58,041 --> 01:25:58,916 functional properties 687 01:25:58,916 --> 01:26:01,833 a little bit is making polarizers. That's 688 01:26:01,833 --> 01:26:03,875 something that's very low 689 01:26:03,875 --> 01:26:07,000 cost, very easy to do, and looks 690 01:26:07,041 --> 01:26:09,541 really cool, but also reminds students, 691 01:26:09,541 --> 01:26:10,541 "Hey, there's more to life 692 01:26:10,541 --> 01:26:12,125 than strength and Young's 693 01:26:12,125 --> 01:26:14,500 modulus and things like that." Right. So 694 01:26:14,500 --> 01:26:17,625 which one do you like? So I've 695 01:26:17,625 --> 01:26:18,958 tried it a couple of different 696 01:26:19,041 --> 01:26:22,916 ways. I've found the best results with 697 01:26:22,916 --> 01:26:24,333 garbage bags actually. 698 01:26:25,750 --> 01:26:27,708 Polyethylene garbage bags. Yes, 699 01:26:27,958 --> 01:26:29,500 polyethylene garbage bags to be clear. 700 01:26:30,458 --> 01:26:35,458 Well, also to be clear. But the trick 701 01:26:35,458 --> 01:26:37,250 with those is getting 702 01:26:37,250 --> 01:26:40,250 the strain rate right so that you can 703 01:26:40,250 --> 01:26:41,958 strain them far enough to 704 01:26:41,958 --> 01:26:43,916 get some good alignment of the 705 01:26:43,916 --> 01:26:45,916 polymer chains to build in that 706 01:26:45,916 --> 01:26:48,125 anisotropy. So they become polarizing 707 01:26:48,125 --> 01:26:49,750 without actually tearing 708 01:26:49,833 --> 01:26:51,666 them. And that can require a little bit 709 01:26:51,666 --> 01:26:54,291 of a delicate touch, but 710 01:26:54,291 --> 01:26:55,166 it's one of those things 711 01:26:55,166 --> 01:26:56,916 you practice it. And as soon as you get 712 01:26:56,916 --> 01:26:58,083 it right the first time, you 713 01:26:58,083 --> 01:26:59,083 say, "Ah, that's what I have 714 01:26:59,083 --> 01:27:00,958 to do." And it's pretty repeatable after 715 01:27:00,958 --> 01:27:02,708 that. But it's also something you can 716 01:27:02,708 --> 01:27:03,625 have a whole class to 717 01:27:03,750 --> 01:27:06,458 buy a box of garbage bags. No big deal. 718 01:27:07,541 --> 01:27:09,083 Right. But you know what I find the most 719 01:27:09,125 --> 01:27:11,791 challenging part of that is to demo that 720 01:27:11,791 --> 01:27:12,541 in front of the whole 721 01:27:12,541 --> 01:27:14,500 class. They got rid of all 722 01:27:14,500 --> 01:27:18,500 the overhead projectors. Right? That was 723 01:27:18,500 --> 01:27:19,708 the perfect place to demo 724 01:27:19,708 --> 01:27:21,291 it. So if two people held 725 01:27:21,500 --> 01:27:24,333 polarizers, right, show that when you 726 01:27:24,333 --> 01:27:26,041 cross them, it goes black and 727 01:27:26,041 --> 01:27:28,416 open it up. And with those two 728 01:27:28,416 --> 01:27:31,208 people holding those, another person 729 01:27:31,208 --> 01:27:33,208 would come in and stretch the 730 01:27:33,208 --> 01:27:34,708 polyethylene garbage bag and 731 01:27:34,750 --> 01:27:37,000 then rotate it. And while it's not as 732 01:27:37,000 --> 01:27:38,416 even as a polarizer, you can 733 01:27:38,416 --> 01:27:40,708 definitely see all the changes 734 01:27:40,791 --> 01:27:44,916 in the intensity on the screen. But they 735 01:27:44,916 --> 01:27:46,375 got rid of that. And 736 01:27:46,375 --> 01:27:49,916 document cameras don't quite cut it 737 01:27:50,166 --> 01:27:51,958 because not enough light goes through. 738 01:27:53,166 --> 01:27:56,333 And so it's a little harder to do. So I 739 01:27:56,333 --> 01:27:57,166 wish they'd bring back 740 01:27:57,166 --> 01:27:59,625 some overhead projectors just for that 741 01:27:59,625 --> 01:28:01,208 demo. Those things were 742 01:28:01,208 --> 01:28:04,000 great. The other one I really like 743 01:28:04,333 --> 01:28:09,416 is how you can have students feel 744 01:28:09,416 --> 01:28:12,791 entropy. And that of course is 745 01:28:12,791 --> 01:28:13,958 the rubber band one. Have you 746 01:28:13,958 --> 01:28:18,166 seen that one, Tim? Oh, yeah. And so it 747 01:28:18,166 --> 01:28:18,875 turns out that your 748 01:28:18,875 --> 01:28:22,083 forehead is very, very sensitive to 749 01:28:22,250 --> 01:28:24,666 temperature. So if you take a rubber 750 01:28:24,666 --> 01:28:26,916 band, you pull it, stretch 751 01:28:26,916 --> 01:28:31,000 it. And then you know, if you 752 01:28:31,375 --> 01:28:33,250 pull it really quickly and put it to your 753 01:28:33,250 --> 01:28:36,458 head, it feels hotter. And 754 01:28:36,458 --> 01:28:38,125 why is that? Because all those 755 01:28:38,125 --> 01:28:41,250 elastomers are sliding along each other, 756 01:28:41,250 --> 01:28:43,208 creating friction, and 757 01:28:43,208 --> 01:28:45,583 it's getting heated, just dual 758 01:28:45,583 --> 01:28:49,041 heating, right? But then if you take your 759 01:28:49,041 --> 01:28:51,000 stretched out polymer and 760 01:28:51,000 --> 01:28:52,708 you release it very quickly and 761 01:28:52,791 --> 01:28:55,291 put it on your head, it is noticeably 762 01:28:55,291 --> 01:28:57,916 cold. Cooler. Yeah. It's 763 01:28:57,916 --> 01:29:00,250 colder than your ambient was. 764 01:29:01,375 --> 01:29:04,583 And why is that? That's because all those 765 01:29:04,583 --> 01:29:07,125 ordered chains have disordered 766 01:29:08,250 --> 01:29:10,083 and entropy and temperature are 767 01:29:10,083 --> 01:29:13,166 intrinsically related. And so you can 768 01:29:13,166 --> 01:29:15,791 feel entropy. And what 769 01:29:15,791 --> 01:29:18,541 I like about this one is every single 770 01:29:18,541 --> 01:29:19,958 student gets to do the demo 771 01:29:19,958 --> 01:29:22,166 themselves, which is ideal. 772 01:29:23,083 --> 01:29:24,958 Unfortunately, with large classes, we 773 01:29:24,958 --> 01:29:27,166 can't always do that. But 774 01:29:27,166 --> 01:29:28,666 with rubber bands are so cheap, 775 01:29:28,875 --> 01:29:30,666 you can pass them all around. Then you 776 01:29:30,666 --> 01:29:31,458 see everybody pulling 777 01:29:31,458 --> 01:29:33,333 these things and it's just 778 01:29:33,333 --> 01:29:36,375 clicking it on the floor. And you know, 779 01:29:36,500 --> 01:29:38,333 entropy is a hard concept to understand. 780 01:29:39,708 --> 01:29:42,041 And hopefully this will give them some 781 01:29:42,041 --> 01:29:44,708 insight into it. And the 782 01:29:44,708 --> 01:29:46,208 very fact that polymers are 783 01:29:46,250 --> 01:29:48,041 these big chains that are either ordered 784 01:29:48,041 --> 01:29:50,958 or disordered, it should 785 01:29:50,958 --> 01:29:53,000 work. And that's one that 786 01:29:53,000 --> 01:29:57,375 almost always works. The other demo I 787 01:29:57,375 --> 01:29:59,083 really like is when you 788 01:29:59,083 --> 01:30:05,500 teach fatigue. So fatigue is 789 01:30:05,916 --> 01:30:08,958 very statistical in nature. It's not 790 01:30:08,958 --> 01:30:16,916 very, what's the word? It doesn't, oh, 791 01:30:16,916 --> 01:30:17,791 there's a word for this. 792 01:30:21,791 --> 01:30:24,083 It doesn't follow from first principles, 793 01:30:24,083 --> 01:30:25,166 right? It's not 794 01:30:25,166 --> 01:30:29,958 reproducible in the way that, 795 01:30:30,333 --> 01:30:32,375 you know, the number of dislocations when 796 01:30:32,375 --> 01:30:34,708 you strain something might be. And 797 01:30:36,500 --> 01:30:40,750 it's, there is a lot of noise and it's 798 01:30:40,750 --> 01:30:44,708 because the origin of fatigue 799 01:30:44,708 --> 01:30:47,500 is a flaw. And you don't know 800 01:30:47,666 --> 01:30:49,708 what the flaws are or how they're 801 01:30:49,708 --> 01:30:51,250 distributed in the material. 802 01:30:52,166 --> 01:30:54,000 So when you stress, even though 803 01:30:54,000 --> 01:30:56,958 you're doing it well below the yield 804 01:30:56,958 --> 01:31:01,291 stress, you're still accumulating defects 805 01:31:01,291 --> 01:31:02,958 and accumulating and 806 01:31:03,625 --> 01:31:06,750 changing internal flaws, cracks, all of 807 01:31:06,750 --> 01:31:08,541 this stuff. So finally, 808 01:31:08,541 --> 01:31:10,583 when you do it too much, 809 01:31:10,583 --> 01:31:13,041 it catastrophically fails. And that's why 810 01:31:13,041 --> 01:31:15,000 fatigue is so dangerous. So 811 01:31:15,000 --> 01:31:17,333 little things like when, you 812 01:31:17,333 --> 01:31:19,458 know, you teach mechanical properties, 813 01:31:19,458 --> 01:31:20,416 you want students to 814 01:31:20,416 --> 01:31:22,708 understand how to calculate an 815 01:31:22,708 --> 01:31:25,458 appropriate safety factor. And it's 816 01:31:25,458 --> 01:31:26,791 usually pretty easy. You 817 01:31:26,791 --> 01:31:28,791 choose at least two, maybe 10, 818 01:31:29,375 --> 01:31:31,833 and you just multiply, you know, the 819 01:31:31,833 --> 01:31:34,500 expected maximum yield 820 01:31:34,500 --> 01:31:36,291 strength and stress that you're 821 01:31:36,291 --> 01:31:38,458 going to have on it and you're done. You 822 01:31:38,458 --> 01:31:41,666 can't do that with fatigue because for 823 01:31:41,666 --> 01:31:43,250 fatigue, you need to 824 01:31:43,250 --> 01:31:45,916 understand the probabilistic nature of 825 01:31:45,916 --> 01:31:48,500 how it fails. So those SN 826 01:31:48,500 --> 01:31:50,125 curves, those are just the 50% 827 01:31:50,500 --> 01:31:53,541 line curves. What really matters is how 828 01:31:53,541 --> 01:31:54,833 all the data is collected 829 01:31:54,833 --> 01:31:57,083 and how it distributes. So the 830 01:31:57,208 --> 01:32:00,250 90th percentile, how far away from that 831 01:32:00,250 --> 01:32:02,416 50% line is that? And 832 01:32:02,416 --> 01:32:03,416 that's going to be different for 833 01:32:03,416 --> 01:32:05,291 different materials, different processing 834 01:32:05,291 --> 01:32:08,333 conditions, it's complicated. So to try 835 01:32:08,333 --> 01:32:09,583 to illustrate that to 836 01:32:09,583 --> 01:32:12,833 students, we give them paperclips and 837 01:32:12,833 --> 01:32:14,208 make a quarter of the class 838 01:32:14,208 --> 01:32:16,583 bend at 90 degrees and back, 839 01:32:16,583 --> 01:32:18,666 that's one cycle, and they keep doing 840 01:32:18,666 --> 01:32:20,916 that. And each person reports 841 01:32:20,916 --> 01:32:23,250 their own number of cycles to 842 01:32:23,291 --> 01:32:26,666 failure. Then the next quarter of the 843 01:32:26,666 --> 01:32:30,083 class does 180 and back, 180 and back. 844 01:32:30,708 --> 01:32:32,208 The next one does 270, 845 01:32:32,625 --> 01:32:35,416 and the last group does 360. Well, the 846 01:32:35,416 --> 01:32:37,208 360 group, of course, those 847 01:32:37,208 --> 01:32:38,625 are going to fail much earlier. 848 01:32:39,291 --> 01:32:40,750 But you're also going to get a much 849 01:32:40,750 --> 01:32:43,000 bigger spread of the data. And when we 850 01:32:43,000 --> 01:32:44,083 look at the raw data, 851 01:32:44,083 --> 01:32:46,250 we can show the students using the class 852 01:32:46,250 --> 01:32:48,625 collectively how much 853 01:32:48,625 --> 01:32:50,375 spread in the data there is 854 01:32:50,583 --> 01:32:53,666 and how that spread changes for each of 855 01:32:53,666 --> 01:32:55,083 these different, well, we 856 01:32:55,083 --> 01:32:56,208 call them loadings. It's 857 01:32:56,208 --> 01:32:58,916 really not quite fatigue, but it's a 858 01:32:58,916 --> 01:33:00,416 strained version of it. 859 01:33:01,125 --> 01:33:02,416 And I think that's a really 860 01:33:02,416 --> 01:33:04,833 valuable thing. And it helps them 861 01:33:04,833 --> 01:33:08,458 understand that. The other demo we do, 862 01:33:09,666 --> 01:33:10,750 it's gotten a little, 863 01:33:12,541 --> 01:33:15,666 what's the word? It's what we used to do, 864 01:33:15,666 --> 01:33:17,041 we don't do anymore, because 865 01:33:17,041 --> 01:33:18,208 some people get embarrassed. 866 01:33:18,583 --> 01:33:21,666 We used to do ask everybody to report 867 01:33:21,666 --> 01:33:24,708 their weight in pounds. And 868 01:33:24,708 --> 01:33:25,958 even though it was anonymous, 869 01:33:26,000 --> 01:33:28,291 people got upset about it. So now we do 870 01:33:28,291 --> 01:33:30,791 height. We ask everybody to 871 01:33:30,791 --> 01:33:32,458 report their height in inches. 872 01:33:33,458 --> 01:33:38,291 And then we show the height average and 873 01:33:38,291 --> 01:33:39,541 the number average 874 01:33:39,541 --> 01:33:42,708 difference of those sets to talk about 875 01:33:42,750 --> 01:33:45,625 polymers with different lengths of 876 01:33:45,625 --> 01:33:47,708 change, just to show them 877 01:33:47,708 --> 01:33:48,958 that you get different results, 878 01:33:48,958 --> 01:33:51,166 depending on how you count and why it 879 01:33:51,166 --> 01:33:53,041 might be important. So 880 01:33:53,041 --> 01:33:54,375 those kinds of demonstrations, 881 01:33:54,666 --> 01:33:57,541 those are still participatory, they might 882 01:33:57,541 --> 01:33:59,875 not be physical, but you're still 883 01:33:59,875 --> 01:34:01,416 illustrating a point. 884 01:34:02,708 --> 01:34:05,541 That's important. One demo I'd love to 885 01:34:05,541 --> 01:34:07,125 do, I don't know if we can pull this off, 886 01:34:07,625 --> 01:34:09,916 but it's the DaVinci demo. Do you know 887 01:34:09,916 --> 01:34:11,750 which one that is? No, 888 01:34:11,750 --> 01:34:14,250 what's that? So Leonardo DaVinci, 889 01:34:15,375 --> 01:34:18,166 way back when he was alive, he did 890 01:34:18,166 --> 01:34:20,291 experiments and he proved 891 01:34:20,291 --> 01:34:23,416 that ropes that were longer 892 01:34:23,833 --> 01:34:26,291 were weaker than ropes that were shorter. 893 01:34:27,875 --> 01:34:28,708 And this usually 894 01:34:28,708 --> 01:34:30,458 blows our students' mind, 895 01:34:30,458 --> 01:34:32,666 you know, the ropes are the same. But of 896 01:34:32,666 --> 01:34:35,083 course, it was because 897 01:34:35,083 --> 01:34:36,500 of Weibull statistics. 898 01:34:38,416 --> 01:34:41,541 And Weibull statistics is just weak link 899 01:34:41,541 --> 01:34:44,750 theory. So the longer a rope is, 900 01:34:44,750 --> 01:34:46,625 statistically, you're 901 01:34:46,625 --> 01:34:48,708 going to have more flaws in the longer 902 01:34:48,708 --> 01:34:51,541 rope, bigger flaws, leading to it 903 01:34:51,541 --> 01:34:53,500 failing, because you'll have 904 01:34:53,500 --> 01:34:55,541 a better chance of a weak link and a long 905 01:34:55,541 --> 01:34:56,958 rope than a short rope. 906 01:34:57,458 --> 01:34:59,333 And DaVinci did that. That's 907 01:34:59,333 --> 01:35:02,166 pretty cool that he did that. And so it'd 908 01:35:02,166 --> 01:35:03,416 be really fun if we had 909 01:35:03,416 --> 01:35:04,708 like some really long ropes 910 01:35:05,125 --> 01:35:08,250 and enough heavy weights to actually see 911 01:35:08,250 --> 01:35:09,500 them break. It would 912 01:35:09,500 --> 01:35:11,000 probably get expensive and take 913 01:35:11,000 --> 01:35:14,458 a lot of space up. But it's kind of a 914 01:35:14,458 --> 01:35:17,875 cool thing that he did that well before 915 01:35:17,875 --> 01:35:19,208 Weibull did his Weibull 916 01:35:19,458 --> 01:35:23,125 statistics. Yeah, that would be an 917 01:35:23,125 --> 01:35:25,583 interesting one to try to turn into a 918 01:35:25,583 --> 01:35:28,000 full class activity, 919 01:35:28,208 --> 01:35:31,291 it'd be a matter of testing out different 920 01:35:31,291 --> 01:35:32,083 types of ropes, different 921 01:35:32,083 --> 01:35:33,541 amounts of weight, so on to 922 01:35:33,583 --> 01:35:35,875 figure out what gives results that are 923 01:35:35,875 --> 01:35:37,166 sort of messy enough, but 924 01:35:37,166 --> 01:35:40,500 still work. And we kind of do 925 01:35:40,500 --> 01:35:42,583 that with one of our projects we do in 926 01:35:42,583 --> 01:35:45,916 our MyIntro class, because I 927 01:35:45,916 --> 01:35:47,291 don't give exams, I have a lot 928 01:35:47,291 --> 01:35:49,458 of time, and because I don't lecture, I 929 01:35:49,458 --> 01:35:51,666 have a lot of time. So for 930 01:35:51,666 --> 01:35:53,500 the part of the class where we 931 01:35:53,500 --> 01:35:56,208 cover mechanical properties, my project 932 01:35:56,208 --> 01:35:59,000 is to build a mechanical testing 933 01:35:59,000 --> 01:36:00,625 instrument out of garbage, 934 01:36:01,000 --> 01:36:04,000 you can't spend more than five bucks. And 935 01:36:04,000 --> 01:36:04,875 so students are 936 01:36:04,875 --> 01:36:07,500 constantly, you know, taking thread, 937 01:36:08,041 --> 01:36:11,208 or taking a laffy toffee and clamping 938 01:36:11,208 --> 01:36:12,750 things to them and looking how it 939 01:36:12,750 --> 01:36:14,291 stresses or strains or 940 01:36:14,291 --> 01:36:17,625 breaks. And it's a lot of fun. And that's 941 01:36:17,625 --> 01:36:19,791 another way to have students 942 01:36:19,791 --> 01:36:21,333 come up with their own demos 943 01:36:21,625 --> 01:36:23,625 is a really fun way. And then of course, 944 01:36:23,625 --> 01:36:25,125 they have to explain to 945 01:36:25,125 --> 01:36:27,166 experts walking around the room, 946 01:36:27,708 --> 01:36:29,791 why it happened. But it's just more 947 01:36:29,791 --> 01:36:31,291 engagement, and it's more 948 01:36:31,291 --> 01:36:33,041 physical. And again, it just 949 01:36:34,250 --> 01:36:36,750 helps the student understand in a 950 01:36:36,750 --> 01:36:39,041 different context than just reading a 951 01:36:39,041 --> 01:36:40,416 book and doing homework 952 01:36:40,416 --> 01:36:43,458 problems, how these phenomena actually 953 01:36:43,458 --> 01:36:45,333 work, so that they can 954 01:36:45,333 --> 01:36:46,916 use the concepts that we're 955 01:36:46,916 --> 01:36:49,208 trying to teach them for whatever they do 956 01:36:49,208 --> 01:36:54,750 in the future. So what other demos? 957 01:36:55,458 --> 01:36:56,125 You've worked on a lot 958 01:36:56,166 --> 01:36:57,916 of demos. I don't know if you have the 959 01:36:57,916 --> 01:37:00,333 list I just gave you, but you can talk 960 01:37:00,333 --> 01:37:01,166 about some of those. 961 01:37:02,041 --> 01:37:05,458 Yeah, I suppose we should round out with 962 01:37:05,458 --> 01:37:06,708 a couple of ceramics 963 01:37:06,708 --> 01:37:09,916 oriented ones. So the first one that 964 01:37:09,916 --> 01:37:12,958 comes to my mind, I love this. This is 965 01:37:12,958 --> 01:37:13,958 also one that requires a 966 01:37:13,958 --> 01:37:15,750 little bit of finesse. But it is 967 01:37:15,750 --> 01:37:17,750 glass the conductor, I learned this one 968 01:37:17,750 --> 01:37:19,333 from the ASM teachers camps, 969 01:37:19,333 --> 01:37:21,166 actually, I've gotten several 970 01:37:21,208 --> 01:37:23,708 demos from them over the years. And the 971 01:37:23,708 --> 01:37:25,541 way you have this set up is 972 01:37:25,541 --> 01:37:27,583 that you've got a light bulb, 973 01:37:28,708 --> 01:37:33,333 and you have an open switch, essentially 974 01:37:33,333 --> 01:37:34,583 in the circuit feeding the 975 01:37:34,583 --> 01:37:35,791 light bulb, and you bridge 976 01:37:35,791 --> 01:37:38,708 that switch with a glass rod. And of 977 01:37:38,708 --> 01:37:39,291 course, the light bulb 978 01:37:39,291 --> 01:37:40,625 doesn't light up because glass is an 979 01:37:40,625 --> 01:37:45,250 insulator, allegedly. But what people 980 01:37:45,250 --> 01:37:46,833 often forget is that 981 01:37:46,833 --> 01:37:48,416 processing is really important. 982 01:37:49,375 --> 01:37:53,000 And the the demo, what you do is you heat 983 01:37:53,000 --> 01:37:55,125 the glass rod with a blowtorch. 984 01:37:56,291 --> 01:37:59,250 And as it gets hot enough, the mobility 985 01:37:59,250 --> 01:38:01,583 of the sodium ions in the 986 01:38:01,583 --> 01:38:02,916 glass, so you do want to use 987 01:38:02,916 --> 01:38:06,083 soda lime glass for this, it'll have a 988 01:38:06,083 --> 01:38:07,166 higher density of sodium 989 01:38:07,166 --> 01:38:09,500 ions in it, they get enough 990 01:38:09,500 --> 01:38:12,125 mobility to where they can actually carry 991 01:38:12,125 --> 01:38:14,416 enough current to light the 992 01:38:14,416 --> 01:38:17,708 light bulb. And if you really 993 01:38:17,833 --> 01:38:20,166 nail it just right, you can actually get 994 01:38:20,166 --> 01:38:21,791 it to self sustain as well 995 01:38:21,791 --> 01:38:23,041 where you take away the torch, 996 01:38:23,541 --> 01:38:25,375 and the resistive heating from the 997 01:38:25,375 --> 01:38:27,291 current passing through the glass will 998 01:38:27,291 --> 01:38:28,333 keep the glass hot enough 999 01:38:28,333 --> 01:38:30,166 to keep the mobility high enough that 1000 01:38:30,166 --> 01:38:32,208 current can keep flowing. And 1001 01:38:32,208 --> 01:38:35,541 the the ASM master teachers who 1002 01:38:35,541 --> 01:38:38,125 have done this a zillion times, I've seen 1003 01:38:38,125 --> 01:38:39,333 them keep one going for 1004 01:38:39,333 --> 01:38:41,500 something like 20 minutes before it 1005 01:38:41,500 --> 01:38:44,666 finally petered out. But yeah, conducting 1006 01:38:44,666 --> 01:38:45,458 electricity through 1007 01:38:45,458 --> 01:38:46,916 glass with the application 1008 01:38:47,041 --> 01:38:49,916 of just a little heat, that's always a 1009 01:38:49,916 --> 01:38:52,666 winner for me. Well, and it's also really 1010 01:38:52,666 --> 01:38:54,041 important to explain 1011 01:38:54,041 --> 01:38:58,166 to students that it's not just electrons 1012 01:38:58,166 --> 01:39:00,083 that transport charge, 1013 01:39:00,625 --> 01:39:02,750 right? Many things can transport 1014 01:39:02,791 --> 01:39:05,333 charge, it's a charge carrier, not an 1015 01:39:05,333 --> 01:39:07,125 electron. Some things are 1016 01:39:07,125 --> 01:39:08,416 holes that are the dominant 1017 01:39:08,875 --> 01:39:11,583 carrier. Some things are ions, like in 1018 01:39:11,583 --> 01:39:13,375 the example you just showed, 1019 01:39:13,791 --> 01:39:15,333 sometimes they're solitons, 1020 01:39:15,375 --> 01:39:17,708 you know, double bond flipping, that make 1021 01:39:17,708 --> 01:39:19,958 things move. So it's 1022 01:39:19,958 --> 01:39:23,125 the fact that the ideas of 1023 01:39:23,125 --> 01:39:26,708 conductivity and resistivity are very 1024 01:39:26,708 --> 01:39:29,625 general, and they span across many 1025 01:39:29,625 --> 01:39:30,791 different kinds of charge 1026 01:39:30,791 --> 01:39:32,583 carriers. And that's a really important 1027 01:39:32,583 --> 01:39:35,208 thing to get students to 1028 01:39:35,208 --> 01:39:37,000 understand. So it's great for them 1029 01:39:37,000 --> 01:39:40,000 understanding glasses, but it's also 1030 01:39:40,000 --> 01:39:40,666 great for them 1031 01:39:40,666 --> 01:39:42,208 understanding electrical properties. 1032 01:39:42,875 --> 01:39:47,541 Yep. What about the making copper for 1033 01:39:47,541 --> 01:39:49,583 malachite? That's another ceramics one. 1034 01:39:50,625 --> 01:39:52,625 Oh, yeah, rocks are ceramics after all. 1035 01:39:53,333 --> 01:39:56,083 There's this is one that is 1036 01:39:56,083 --> 01:39:58,583 so fun to do with students, 1037 01:39:59,333 --> 01:40:00,750 partly, of course, it involves smoke and 1038 01:40:00,750 --> 01:40:01,500 fire. And so that's 1039 01:40:01,500 --> 01:40:05,250 exciting. But it's a really great 1040 01:40:05,250 --> 01:40:07,916 illustration of this very, very old 1041 01:40:07,916 --> 01:40:09,500 process of turning rocks into 1042 01:40:09,500 --> 01:40:12,125 metal. This is, I don't know, 1043 01:40:12,333 --> 01:40:14,666 5000 years old technology at this point, 1044 01:40:15,083 --> 01:40:16,250 and still quite relevant 1045 01:40:16,250 --> 01:40:18,416 today. So how it's set up 1046 01:40:19,708 --> 01:40:23,083 is that you get a piece of charcoal, not 1047 01:40:23,083 --> 01:40:24,583 like a brick hat, but a 1048 01:40:24,583 --> 01:40:26,583 good lump hardwood charcoal 1049 01:40:26,708 --> 01:40:29,166 large piece. This is your carbon source. 1050 01:40:30,083 --> 01:40:34,958 And you can carve or drill a 1051 01:40:34,958 --> 01:40:37,500 well, you're making a crucible 1052 01:40:37,875 --> 01:40:40,666 right in the charcoal, and you load it up 1053 01:40:40,666 --> 01:40:42,958 with some flakes of 1054 01:40:42,958 --> 01:40:46,833 malachite. And you heat it. Again, 1055 01:40:47,000 --> 01:40:51,083 I use a torch. And as you heat it, you're 1056 01:40:51,083 --> 01:40:53,041 going through a series of 1057 01:40:53,041 --> 01:40:55,000 chemical reactions, where 1058 01:40:55,375 --> 01:40:59,041 you are making carbon monoxide and carbon 1059 01:40:59,041 --> 01:41:02,916 dioxide as you as you make 1060 01:41:02,916 --> 01:41:04,125 the charcoal react with the air. 1061 01:41:04,791 --> 01:41:10,666 And then you have the reactions between 1062 01:41:10,666 --> 01:41:13,458 the malachite, which I'm 1063 01:41:13,458 --> 01:41:14,166 trying to get this from 1064 01:41:14,166 --> 01:41:16,583 memory, I think it's a copper carbonate 1065 01:41:16,583 --> 01:41:21,250 hydrate, maybe. But you are you're 1066 01:41:21,250 --> 01:41:22,875 dehydrating the rock, 1067 01:41:23,541 --> 01:41:27,041 and you're also de carbonate thing. 1068 01:41:27,750 --> 01:41:29,333 That's not a word. But you're 1069 01:41:29,333 --> 01:41:30,458 pulling the carbonate out of 1070 01:41:30,500 --> 01:41:34,208 the rock, as it reacts with the, the 1071 01:41:34,208 --> 01:41:36,041 carbon monoxide, and the 1072 01:41:36,041 --> 01:41:38,291 oxygen in the air in this 1073 01:41:38,416 --> 01:41:40,250 hot air that you're making. And what you 1074 01:41:40,250 --> 01:41:42,166 end up with is nothing left 1075 01:41:42,166 --> 01:41:44,375 but the copper. And the way 1076 01:41:44,375 --> 01:41:46,500 it looks visually, it's hard to describe 1077 01:41:46,500 --> 01:41:48,125 this in words, but you 1078 01:41:48,125 --> 01:41:49,250 start with this green rock, 1079 01:41:49,375 --> 01:41:51,083 and you heat it, and it gets glowing hot. 1080 01:41:51,708 --> 01:41:53,000 And students are like, 1081 01:41:53,000 --> 01:41:54,125 Okay, is anything happening, 1082 01:41:54,125 --> 01:41:55,875 you're just making the rock glow because 1083 01:41:55,875 --> 01:41:57,458 it's hot. But then 1084 01:41:57,458 --> 01:41:58,416 after a couple minutes, 1085 01:41:58,500 --> 01:42:00,541 you take away the flame, and you let it 1086 01:42:00,541 --> 01:42:02,583 cool down. And it's 1087 01:42:02,583 --> 01:42:04,875 still red. And they're like, 1088 01:42:04,875 --> 01:42:08,083 Why is it red? Well, you tell me, you 1089 01:42:08,083 --> 01:42:09,500 took high school chemistry, what is a 1090 01:42:09,500 --> 01:42:10,625 color change indicate, 1091 01:42:10,625 --> 01:42:12,250 and they're like, Oh, chemical reaction. 1092 01:42:12,708 --> 01:42:14,916 So we go through this. And 1093 01:42:14,916 --> 01:42:17,500 then I pull out these little 1094 01:42:17,750 --> 01:42:20,166 red rocks that I've made, hit them with a 1095 01:42:20,166 --> 01:42:22,125 hammer, and they don't break. They're 1096 01:42:22,125 --> 01:42:23,333 ductile, they smoosh, 1097 01:42:23,375 --> 01:42:26,083 they smear. And so then it's just another 1098 01:42:26,083 --> 01:42:28,083 one of those, huh, I 1099 01:42:28,083 --> 01:42:29,125 thought ceramics were brittle, 1100 01:42:29,208 --> 01:42:31,250 what happened? And eventually someone is 1101 01:42:31,250 --> 01:42:32,625 like, Oh, it's red because 1102 01:42:32,625 --> 01:42:33,791 it's copper, you turned it into 1103 01:42:33,791 --> 01:42:37,791 a metal. Yeah. So wonderful demo. Love 1104 01:42:37,791 --> 01:42:40,291 that. I learned that from 1105 01:42:40,291 --> 01:42:42,791 Kevin Jones actually props to 1106 01:42:42,791 --> 01:42:45,666 him for being my inspiration on that one. 1107 01:42:46,250 --> 01:42:47,458 But yeah, I love that for 1108 01:42:47,458 --> 01:42:49,166 sure. I even like if you 1109 01:42:49,208 --> 01:42:52,250 watch carefully, once it turns to copper, 1110 01:42:52,916 --> 01:42:53,958 the flame from the 1111 01:42:53,958 --> 01:42:55,916 blowtorch, you start seeing little 1112 01:42:55,916 --> 01:42:58,333 bits of green green, because you may 1113 01:42:58,333 --> 01:43:00,666 remember from your inorganic chemistry 1114 01:43:00,666 --> 01:43:02,958 lab course, that the color 1115 01:43:03,208 --> 01:43:06,291 of the gases tell you something about 1116 01:43:06,291 --> 01:43:07,875 what materials are 1117 01:43:07,875 --> 01:43:12,000 there. So it's kind of cool. 1118 01:43:12,958 --> 01:43:16,958 Anyway, there are tons more demos. I 1119 01:43:16,958 --> 01:43:18,041 think we're out of time. I 1120 01:43:18,041 --> 01:43:19,958 just realized this. We're at the 1121 01:43:19,958 --> 01:43:23,000 45 minute mark. Oh, my goodness. So talk 1122 01:43:23,000 --> 01:43:24,208 about demos all day, but I 1123 01:43:24,208 --> 01:43:25,583 won't, we should wrap it up. 1124 01:43:27,000 --> 01:43:31,750 So we'll wrap this up and let me play our 1125 01:43:31,750 --> 01:43:34,708 outro music. So with 1126 01:43:34,708 --> 01:43:36,291 that, thanks for joining us. 1127 01:43:36,416 --> 01:43:38,000 And we'll see you next 1128 01:43:38,000 --> 01:43:39,541 time. See you next time.