Archive for the ‘Activities’ Category
I’ve been a member of American Association of Physics Teachers for about 6 years now. If you teach physics, please join! The journals and posters alone are worth the tax deductable annual dues. I attended my first AAPT meeting a couple of weeks back. I learned one or two great new things, met some super people, but I was also a bit disappointed.
Let’s get the negative stuff out of the way.
- I’m used to NSTA, so maybe my reference is unfair. AAPT was small, really small for a national conference. I felt like everybody knew each other because it was the same people every year. You could get through the entire exhibit areas in about an hour.
- It also felt like the conference was aimed at college educators. I know the organizers claim it’s not, but I’m giving my opinion here based on attending one day of a much longer conference.
- I had hoped that the talk on video in the classroom would give lots of useful tips; how to integrate video, success at flipping the classroom, etc. Most of the discussion was why video lectures won’t replace colleges.
Now the positives:
- The first timer special and lunch was a great idea. Lunch and the company was terrific, I’m glad I went. The first timer $75 one-day special is a great way to try it out.
- I got to meet some great people, some new, some who I had previously met online (Kathy, Frank). Everybody was warm and there to interact and learn from each other.
- I met local AAPT members who are trying to suck me in to local activities. I am interest, but they always do them on a Friday night and Saturday. I may submit, I do need local physics buddies but I love my weekends.
- Andy Rundquist demonstrated a great use of Jing. He has his students take a picture of their homework, then narrate the work on video. The video is their homework submission. Jing limits them to 5 minutes and when they talk, you can immediately tell if they know what they are talking about. Andy has them do this for every homework, I’m going to use it sparingly. Super idea.
- There is free software out there called Tracker that does video analysis. One cool use was to take a moving object, like a person jumping into the water, identify several points (hands, feet, head) through each frame, and let the software determine the center of gravity and plot the motion. Did I mention free?
- I really like the sessions where there is a new presenter every 10 minutes. Lots of great stuff, and if it isn’t, it’s only 10 minutes until the next one.
AAPT was worth my time, I wish I had done the entire week. It was close enough to home that I was able to take public transportation. Here’s the problem: if you can get your school to pay for you to travel to one national conference, which do you choose – AAPT or NSTA?
For me, it would be an easy choice. NSTA has so much more to offer, so many more strands, talks, exhibitors, and people to interact with. I would love to do both, I don’t see how. I will get involved locally, AAPT is too good of an organization to ignore, they are worthy of our support.
This is not a new topic for me, it’s been a burr in my saddle for some time now. All of the introductory physics textbooks address significant figures in much the same way. The problem is – nobody in the “real world” uses sig figs. At the same time, introductory physics isn’t the time to introduce complex error analysis models.
I’m having this discussion with Andy Rundquist of Hamline University. I asked Andy how they handled this at the college level. He told me they don’t teach significant figures and pointed me to a very lengthy article discussing why significant figures are all wrong. The article suggests the use of Monte Carlo analysis its place. That may make sense on a lab, but not on classwork and homework problems. The uncertainty article did have a suggestion; use six significant figures for calculations and round the final answer to three sig figs. The article does a good job explaining the reasoning, and I’m fine with it. The three extra “guard digits” preserve the accuracy, and the rounding makes the answer more reasonable.
- I will project an archery target on the board.
- Students will move back about 20 feet and shoot a round of Nerf darts at the target. They will be far enough back that most of them will shoot a 6, or 7 and not a 9 or 10, at least at first. Each student will take a turn.
- We will plot the overall results. We should get something resembling a normal distribution curve, but I won’t tell them that.
- I will ask the kids to average the data and come up with a value of x.x +/- y.y and start a discussion on whether or not that represents the data.
- We will then put a ring or other object on an electronic scale and write the mass with the error in the same way.
- After some discussion, I will bring up slides of normal, rectangular, triangular, and maybe exponential distribution curves. I want them to discuss the fit of the models to the data.
- My goal is that they understand that error is probability.
- About a week later we will drop rulers and calculate individual reaction times. This would be a good time to bring back the distribution graphs and perhaps even input our data into a statistical analysis program to find the best fit.
I think this will work and go over well. I’d love some feedback. It’s a first pass, what did I miss?
First, let me be completely up front. I borrowed this activity from my pal Deborah Carder. You can find her link in my blogroll, she does great hands-on activities and labs. I met her at NSTA Philly last year, she is the Energizer Bunny of science teachers, I don’t know how she does it.
Anyway, as I had mentioned in earlier posts on momentum, I wanted to do the egg drop competition, but I’m in a one-story building. This year we are doing the “Egg Crash” competition. The basic concept is that teams get 10 sheets of computer paper, 1 meter of masking tape, a pair of scissors, and 20 minutes to construct a free-standing object to safely catch the egg. They drop their own egg from a height starting at 0.5 meters above the top of their structure. The egg is inspected before and after each drop, the higher they go, the more points they win. The surviving eggs are dropped from 0.5 meters higher each round until they all finally break.
I usually allot 25 points for a lab, I will probably go 50 for this one. Deb said she does 100 points, but that’s a test grade and I don’t think a one-day lab should be worth that much. I’m still working out the scoring, but I think I will assign a grade to each height. If they fail at 0.5 m above their structure, they get 30/50, but they also get a single start-over with a new egg. Each 0.5 m interval earns 5 more points. That means surviving 2.0 m earns 50/50. I’m willing to give 5 or 10 extra credit points if they can survive a drop from 2.5 or 3.o meters over the top. I was going to do direct competition for the points, but what if everyone fails at 1.0 meters? With my grading system, they all get 70% since nobody really earned the A or B.
I handed out the Egg Crash Description and Rules on the day we started learning about Momentum. I told them it will be about a week before we do the competition; I wanted them thinking about the problem and their design as we learn about momentum and impulse. This week I will show a great video called “Car Crash Tech.” The video discusses the state of the art auto safety systems and the effects of air bags and other innovations.
I’m hoping for some creative solutions from the kids. Maybe I’ll have a picture or two to post here in a couple of weeks.
Okay, I’ve been a bad boy. It was more than a year ago I said I would update the post with the instructions. You guys didn’t call me on it, so I forgot. The original post is here along with a pdf of the plans I had printed for myself:
The original plans make a balloon that is 60 inches high. That is perfect for the classroom, it takes three pieces of tissue paper per panel and you need six panels. You will find I went big on this one and made a 90 inch version for myself. It is rather unwieldy and difficult to handle, but bigger balloon means bigger lift. At this point, I can put one of these 60″ balloon together in about an hour, where it takes the kids at least 2 hours.
One of the challenges we ran into was finding the aluminum wire we used to keep the mouth open. You want this for two important reasons; first, to add ballast; but more importantly, without it, the kids can’t catch the balloons on their heads. I found the wire at Dick Blick, an art supply store. They list it under sculpture wire, we use the 14 gauge wire. It costs $16 for a 350 foot spool. Each balloon uses about 3 feet. That’s a lot of hot air balloons.
When it is too windy outside, we tend to launch these in the gym. I have two heat sources. The indoor one is a heat gun I purchased from Harbor Freight on sale for $10. It works great, I make sure I handle it so nobody gets burned. The outside source is a plumbers propane torch. Nobody handles that but me, I don’t need to write up any (more) accident reports. If you are using the torch, make sure the kids keep the balloon opened up, if you aren’t careful you can catch the balloon on fire. Oops, only did that once, very cool though. If you do that, light it from the bottom, it goes up into the air and disintegrates … poof. Bad science teacher.
Some day I may make one of those cool chimney launchers, but then I’ll have to store it in my room. It’s already looking like Sanford and Sons in my classroom, I don’t know how much more junk I can store.
Tomorrow the students learn just how big our solar system is and just how small we are. We will use the attached worksheet to calculate the percent distance from Pluto for the planets in our solar system and our nearest neighbor, Proxima Centauri.
To make this lesson really stick, we first calculate the percentages, then we lay out a long 100 meter tape outside. Students volunteer to be objects and they get a card with the picture of that object on it. Now we place them on the scale based on their percentage distance. The Sun is at the zero point, Mercury being only 1% of the distance to Pluto is at 1 meter. Earth is at 3 meters, Mars is at 4 meters. Jupiter jumps to 13 meters from the Sun. Pluto is at the 100 meter mark.
In addition to the vast distances, I then discuss how big these objects would be at this scale. The Sun, as huge as it is, is only 2.4 cm or 1 inch in diameter. The Earth would be 0.2 mm, about the size of the period at the end of a sentence.
We discuss how long it takes to get from the Earth to Mars (a 6 month trip by rocket). The people who are Earth and Mars are fighting for space on the tape, it’s crowded near the Sun. After they start to get a sense of scale, I hit them with this. At this scale, the next closes star, Proxima Centauri, is 676 km (420 miles) away, or roughly the distance from Philadelphia to Portland, Maine.
Essentially there is a network of these things out there for researchers and educators and the public to use. You just need to know they exist, and now you do. For non-researchers, these robotic telescopes have their interface simplified to make taking pictures relatively painless and error free. These robots sit in a field, all alone, with nobody to talk to, just taking orders for pictures.
There is only a small catalog of 36 objects, not all of which will be visible that evening. Pick one, then the interface asks you for a field of view. For those of you who have never used a telescope, it is essentially a zoom level. For the common folk, you only have one choice, but you do have to select it. Next is the time of exposure. It gives you several options, but it will tell you if it is too long or too short. Last is the filter. Some objects have no filter, others have red, green, and blue. Click on continue, give them an email address, and you will have your pictures delivered some time the next day. I’ve tried it twice now, each time the pictures have arrived after lunch the following day.
If you aren’t aware of how astronomical photos are made, here is a quick lesson. Pictures are taken through different color filters. Through a telescope or the naked eye, everything is just shades of gray. But if you take it through RGB filters, you end up with three different images. Now you color each of those images separately and use special software to merge them into a single image. Ta-da! A full color image you created.
Okay, there is more. Astronomy photos are typically in a format called fits. These images carry tons of information about where, when, settings, etc. You really need a special package to merge these photos, but you are in luck. On the same page is free software and a tutorial to do all this.
Imagine how excited your students will be. You teach them about how light is gathered by a telescope. You talk about how the filters are needed to show the color. The color is real, we just can’t see it, there aren’t enough photons for our eyes. Next up, the students go to the site and select an object to photograph. Their request goes into the queue. Multiple requests of the same object will each have individual pictures. Now you can have them walk through the tutorial and use their own image to combine and create their own astronomical photo. Once done, I would send the lot off to Walmart or CVS or some other inexpensive photo developer and they get to put their own astronomical photo on the fridge. Seriously, I get goosebumps thinking about this lesson.
Like I said, this little secret was worth the cost of NSTA. And I almost stayed home on Saturday.
Cards on the table… I outright stole this project. My daughter was competing in the Physics Olympiad this weekend and one of the activities was to build a tower of marshmallows and toothpicks that can support a ping pong ball. I know it’s not new, but I had never watched it happen before, I’m sold.
This was a great exercise in teamwork and engineering. I was rather impressed at how the whole project came together in just 25 minutes. I wasn’t sure when I would do this in my classes, we don’t ever really study mechanical engineering principles. The same with the basswood bridges they built. The concepts are great, I love the hands-on, I just wasn’t sure where this would fit in my curriculum. I decided that I am going to use the Tower of Marsh when we do a short chapter on Center of Gravity. We can do a small side study of bridge design and then do a team activity building the towers. I was going to give the kids 40 minutes, the 25 minutes they had seemed to fly by and I have a 55 minute class to fill. Maybe as an added prize, the winning team would get to have hot chocolate with mini-marshmallows.
The attached instruction sheet has been modified for classroom use and includes how it will be scored. This is in Word 2007 format, you may need a the free converter if you don’t have it yet.
I wanted to build this robot, but we just didn’t get that far. I’ll save it for my summer program at the community college. After midterm exams, we came back to the robots for a final two weeks of programming.
First up was the touch sensor. I liked this lesson, it added switch blocks (if-then) into the programming. We used it with the “follow the line” activity, but the training software told the kids what to do. This time they had to do it on their own. By now, the CMU software has become only a guideline and a reference for the kids. Their assignment was to teach the robot to move forward until it bumped into something. When that happened, the robot was supposed to stop, say “sorry,” back up a little, turn, and start over. This is actually an easy program, so while they were figuring this out, I build a maze out of textbooks.
Part two of this got tricky. I stopped class and explained how you can find your way out of any maze by simply hugging either the right or left wall. They had to try to get through the maze using the single touch sensor in the front. Only one of my students got this to work, and I actually gave him the method. I won’t give it away. Most of the kids got frustrated because the robot would enter the maze and just bump around aimlessly. I asked them to brainstorm a method of using two or more sensors to get through the maze.
The general solution was to add the ultrasonic sensor. Rather than add the sensor to the front, we added it to either the right or left side. The idea was to have the robot stay a certain distance from the right wall. But if it hit something while following the right wall, it would need to make a left turn and continue. This took a lot of trial-and-error for them. It required two switch blocks, one first for the ultrasonic sensor, then one for the touch sensor, both of them together in a loop.
I made this more interesting by changing and growing the maze each day and requiring that the robot must enter the maze from point A and exit at point B, then do it in reverse. This eliminated the possibility of somebody getting clever and just teaching the path to their robot. I made it a point challenge, 50 out of 50 for the fastest combined time, 45/50 for completing the maze in both directions, 40/50 for completing it in one direction, and 35/50 for trying until they ran out of time. Slackers got less, mostly 25/50.
The other final 50 point project was an ad campaign for a robot they had to design and market. The kids had to come up with a feature set and figure out who they would sell it to. They had 3 to 5 minutes to present their idea and tell us why their robot would solve our problems. After the presentation, we discussed what in their design existed today, how some of the technology was 20 years old, how some of it is so hard to do. I ended this with Michio Kaku’s new show How to Build a Robot. Final Project
So what did I learn?
- The CMU lesson software is a good starting point for a lesson, but I needed to add a timed point challenge at the end of each training sesson. I will use the CMU lessons in the future, but not rely on them alone.
- It’s really hard to put this stuff on a midterm exam. Best to not try and give them graded programming challenges every day or two.
- Keeping the kids out of the parts bins is a good idea as long as several classes are sharing the robots. Next year when I have a dedicated class, it won’t be an issue. But not letting them modify the robot beyond the guidelines of the lesson was the way to go.
- Number all the big parts to match the brick and bin.
- I started to have the kids delete their programs from the computer and the robot so others wouldn’t cheat. I don’t have a better way around that right now. I’d like to use USB drives, but we’ve had virus issues, so that’s not allowed. Ideally, LEGO will add password protection.
- Invest in some NXT books. I found a bunch on eBay and half.com and went crazy. If you are only purchasing one of them, buy the book “The Lego Mindstorms NXT Idea Book” by Boogaarts, Daudelin, Davis, Kelly, Levy, Morris, … . This is the book I wish I had before I started the course. It tells you how to do all those things you figure out a little too late, like making your own subroutines (it’s so easy) and how each of the sensors work (if you use more than one ultrasonic sensor at a time, they interfere with each other). Also, books by James Kelly have some good challenges based around a storyline. I think this would be a great way to introduce these robots to a middle school class. I have the Mayan Adventure, his newer one is called The King’s Treasure; I’ll be picking that one up as well.
- I will add the “My Blocks” early on. Next time, after the kids complete the first task of programming the robot to travel in rectangle, I’ll show them how they can make a single “My Block” for a 90 degree right turn and just use it rather than cutting and pasting 5 blocks for each turn. Hopefully, they’ll build their own library of additional blocks as the class progresses.
- Download videos of LEGO projects from YouTube. There are a whole bunch of different walking robots, Rubik’s Cube solvers, and an amazing Sudoku solver that you absolutely must see. I plan to show the walking robots to the summer kids and let them go on their own to design and build their own walking creation. The videos showed the kids the power of the “toys” they were playing with. I will show these and other short robot videos, perhaps one at the start of each class, in an effort to motivate them into doing more.
I was worried I wouldn’t have enough material for the kids to do this for 6 hours a day for a week. I’m pretty sure the projects and videos will make the summer session fly by. It should be fun to let them experiment and build on their own.
HELP: If anyone has good NXT plans or links for a walking robot or a dog, or any other plans I can use for this class, I would really appreciate an email. Use the Contact Me or post a comment. Thanks.
A quick update and then a bit of a review. We purchased 12 Lego NXT robot kits for the classes. I was at first concerned that each class needed their own robots – not a problem. We pre-built the robot that the classes are using. Sharing robots has not been an issue, but we aren’t making major changes to the robots either. Basically, as we move along, another sensor is added and stays added. Students have not been in the parts bins and I like that. The kids work in groups of two and have one computer per robot.
The kits were missing some pieces, Lego is great about sending them out without a hassle. There are two different “Taskbots” described; one in the paper manual you get with the kit, the other in the Carnegie Mellon University (CMU) Robotics curriculum. I found out the hard way, you should make the CMU Taskbot, not the Lego Taskbot if you are using CMU classroom software. It took 30-45 minutes per robot to build them from scratch.
I started off using the CMU projects and worksheets as included in the software. After a week, I had about eight hundred pages to grade and the kids were spending more time answering questions than programming. Some were getting bored. I’m still not unburied.
I dropped the worksheets, they just were getting in the way, and to be honest, they were very repetitive. Instead, I had my students follow the lesson in the lesson video (which is very well done) and when they were finished, I had an additional programming assignment they had to complete. I came up with a shorthand programming language so they could quickly copy the program onto paper. At the basic level, there is an icon based programming language that is very user friendly, but hard to document. Their assignments had to be accurately documented so that I could re-create their program. Many of them can’t seem to get that concept, but they will, it’s on the midterm next week.
Some things that helped:
- Number the robots and kits with a Sharpie. That way you can keep sensors and parts together. Like I said, students haven’t been in the kits, so everything is in good shape 3 weeks into the lessons. Each robot behaves slightly differently, the sensors and motors are not exactly alike, so fine tuning programs works better when you keep coming back to the same robot.
- The software has “profiles” for different classes to use the software. Unfortunately, profiles aren’t password protected. There was some problems with students checking out the work from another class. This is hard to catch and is a real pain. If you can have classroom accounts for each class, you would be in better shape. I didn’t have that luxury this year.
- I pay attention each day to who is out, working hard, and hardly working. Part of their grade is an effort grade, a daily log give me a better sense of history.
What worked and what didn’t:
- The first couple lessons were how to move forward and backward. Again, paperwork went slow, but the lesson was a good one because sensors count up and back. If you move forward 2 rotations and want to move back 2 rotations, the sensors have to move back to zero then back to negative 2. So learning how the rotation sensors worked was important.
- At the end of the lesson, I always suggested the students play with the robot enough to teach me something. They learned to add sounds, speech, pictures to the screen, and a few other tricks early on. I encouraged playing and didn’t hassle them as long as they were busy.
- The turning lessons were tedious. It didn’t help that my students can’t get the concept of diameter of the wheel being related to the distance the wheel turns in a single rotation. It wasn’t a bad lesson, my kids are horrible at math. When they finished the turning work (including too much paperwork), I told them they had to teach the robot to do a Figure-8. It took some of them more than two classes to make that happen. I put an “X” on the floor using electrical tape. It was the starting point and they had to end up somewhere near there when they ended. That was a good addition.
- Next up was the sound sensor. The software walked them through “Clap-on, Clap-Off” where a single clap starts and stops the robot. It went on to teach about programming loops as well. My addition (from the software), one clap on, two claps off. They had to turn in a written program to get credit.
- For each added assignment, I created a demo program so they had an idea what I was looking for. I tended to add lots of flash and silliness to my programs. For instance, for the “Clap-On, Clap-Off” program, it would start with Hello. After one clap, it would say “Green Light” and start moving. After two claps, it would stop and say “Red Light.” It would then pause, spin in place 3 times while screaming, stop and say “Sorry,” then start over again.
- This week was “Follow the Line.” This is a great lesson that appears harder than it is. Using the light sensor, you stay either to the right or left of a thick line made from electrical tape. The robot works but crawls. My addition was for them to get creative and try to make it go faster. I put down two paths using tape, we used one as the race track. Using the original program, a robot takes about 3 minutes to do the loop. The battle has been intense, the first record was set at about 26.7 seconds, today someone did it in 19.5 second. The track is kind of like a go-cart track, mostly oval but with an extra indented curve that makes this quite challenging.
- CMU’s fix to the original slow line tracker is to move the sensor closer to the wheels and go in reverse, but my students blew that away with their creative programming using the original plan. I like my way better.
Next is touch sensing and using infrared sensors to detect objects. Unfortunately, that won’t be for two weeks, we need to start reviewing for midterms, they are next week. Expect part two in about a month.
Parents hate them. Most aren’t any more science literate than their kids. The pressure on the parents to create a decent project is awful. Coming up with a good science experiment project is really hard to do. There are dozens of books on the topic and everybody is clawing at them, trying to find something they can handle.
Kids hate them. They see it as a grade, nothing more. They don’t understand the need for the formality in the presentation. All they know is they don’t win. Now they hate science.
Teachers hate them. Be honest, they are brutal to grade, the work is not worth the effort. Please, no more volcanoes.
OK, now that I got that off my chest, let’s talk about this.
I love doing experiments. I love inspiring kids to think. I make my students experiment constantly. I want them to play in science, find the joy and excitement. I want them to ask questions and be curious. I make them launch rockets and throw balls. If they make a paper airplane in my class, they better make five or ten and tell me what design works best and why. Is science really distilling everything they know about a topic and making it fit on a bent poster board?
I will be doing a science fair in my classroom in about a week. Only I don’t call it that. I call it my “Mythbusters Project.” To be honest, I don’t care if it’s a stupid idea they are testing. I want them to be goofy and have fun. I help them to make sure they are doing good science. I challenge their findings. I make them work together and research. I know, it’s not the county science fair. So what?
You can’t sell someone something they don’t want or need. Really, it’s true. OK, maybe once, but you lost them as a customer forever if you do that. Kids want to be creative, they want to think, they want to learn. They are unbelievably curious. If you don’t think so, leave a pile of mechanical puzzles on the table and don’t draw attention to it. Every one of them will be in the kids’ hands in two minutes. Try it.
Here’s the question you need to ask yourself: What can I do to make this kid love science?
I was listening to my iPod this morning and I heard Neil deGrasse Tyson as a guest at a public symposium in Portland, Oregon. It was published as part of the podcast “NOVA scienceNOW.” I’m considering playing it for my class, it’s only 30 minutes long.
This sounds a lot like what goes on in my classroom on Fridays, only way more orderly and with microphones. In my Conceptual Physics classes, my students have an assignment on Wednesdays to print out a bit of science news, any area of science is fine. They need to read the article and highlight key points. I collect these and on Friday we have science news day, where we talk about anything science. I use the articles as a starting point, and we quickly jump from topic to topic. Nothing is off limits, they come up with a million questions. Sometimes they go off and research something further from our discussions.
In addition to using this just to get them thinking about science, I use this to get across certain agenda items. A couple of the news items were cut and pasted into word to make it easier to print. I asked the kids to make sure they note the site it came from, I need the source so I can go back and read more. We talked about good and bad sources. Another student had an article on the 2012 predictions. The first paragraph talked about some scientists needing facts, but the authors were going on “instincts.” I did the pen and shoe drop, asking them about their predictions. I emphasized that scientists guts can be a starting point, but facts are the only things we trust.
This week, an additional assignment is going to be to write a question about science that they have wanted to know the answer to. I’ll may pick from those to get the conversation started or I may put up a “great question” list and let them research a question and present the answer for extra credit.
I was going to imbed the podcast or attach the file for download, but WordPress wants me to upgrade from a free blog to do that. Go to the iTunes store and search for NOVA ScienceNOW. I tried the NOVA website, but they don’t make it any easier to link to the file.
Dr. Tyson has a couple of great responses. One is about using his own children as an experiment in getting kids to be science literate. It’s worth listening to for just that one. There’s more, go listen.
After you listen to it, tell me if you would play it in the classroom. I’m a little wary of audio only, kids tend to listen with their heads on the desks and it can be hard to get them back up.
Update - The kids enjoyed it. At first, they were reluctant (no pictures), but I stopped it half way through and offered to switch to science news. They asked in all three classes to continue the audio. I know they like science news, so that was encouraging. I think they honestly enjoyed the change of pace and learned a little something from someone else.
I love magic. Being a scientist doesn’t take away from the amazement created by a well executed trick. My father sent me a clip of Chris Angel doing a trick where he not cuts, but pulls a woman in half right on a park bench. The trick is incredibly shocking, the people on the set are screaming in fear and surprise. You can see they are visibly shaken.
YouTube video of Chris Angel. I’m going to show this clip and then start a discussion. First question – did he really pull this woman in half? Obviously that did not happen, so what did? The students are going to either work alone or in small groups and try to come up with a way to explain and possibly reproduce the effect.
What I hope to get from this exercise is a little critical thinking. If the woman was not pulled apart, and Chris Angel doesn’t have real magical powers, then it must be a trick. We don’t know how he does it, but we can make educated guesses and then experiment to attempt to reproduce the method.
How do you see light’s path through a lens? We did this experiment at the DAMOP teacher’s workshop at Penn State last year. Make Jello in a flat bottom pan, about 3/4″ deep. Use half the water so the Jello is firmer than normal. You’ll have to experiment with the color and tell me which works best, I haven’t done this on my own yet.
Obviously the Jello is made the day before. Now cut the Jello into the shapes of the lenses. You can make prisms, double concave, convex, whatever you like. You can float the pan in warm water to release the lenses from the pan. Don’t do it too long, just enough for the Jello to lift out undamaged.
Now shine a laser pointer through the Jello. You will be able to see the path of the laser and follow as the light is bent by the lens. Set up a series of lenses and have fun. When you are done, you can eat the experiment.
If you don’t know what a lateral thinking puzzle is, google it. These are great puzzles to make the kids think a little differently. The kids make so many assumptions, I’m always struggling to find ways to open up their thinking process.
I had a period to kill with one of my classes, so I pulled out a few of these puzzles. It’s real important to lay down the rules for the puzzles. They need to take turns asking questions, they get into it, but I can’t answer questions when they talk over each other. The questions have to be in a form that I can answer with yes or no. Sometimes I answer with “doesn’t matter” or “I don’t know” and that irritates them because it wasn’t in the rules. It was, I just didn’t tell them.
The idea is for them to start asking questions and realizing they assumed an incorrect body of information. Here’s an example, it’s so common, I don’t think I’m ruining any great puzzle sharing it.A body is discovered in a park in Chicago in the middle of summer. It has a fractured skull and many other broken bones, but the cause of death was hypothermia.
The solution is usually in the form of a story that the kids need to work out through their questioning. Here is the solution to the above puzzle:
A poor peasant from somewhere in Europe desperately wants to come to the United States. Lacking money for airfare, he stows away in the landing gear compartment of a jet. He dies of hypothermia in mid flight and falls out when the compartment opens as the plane makes it final approach.
Check out some online sources and books at the stores. I have a couple of books, but I find most of the puzzles aren’t good enough to use in class. I might highlight for or five puzzles from a small book of puzzles. Tell me how they work out for you.
I now feel qualified to put something up on this post. We played for two whole days in my physical science class, and the kids still want more. Another day in my three physics classes, and I’m battle ready.
I began by showing the balloon on the bald teacher’s head and sticking it to the wall. Trust me, nothing gets them going more than a mostly bald teacher trying to rub a balloon on his hair. Amazingly, there were quite a few students that had never seen a balloon charged up and stuck to a wall.
We then went to the standard acrylic/fur type of static charge, explaining how the charges separate. I caused paper and bits of styrofoam to jump from the charge.
The van de graaff generator is exactly like those static creating devices, but it just keeps making more and more static. Here are a few ideas I have either done or picked up on the internet. One important note; I got all of the kids up and involved. Some of them were scared, but after the girls charged up their hair without pain, the chickens were shamed into bravery.
Before doing each of these demonstrations, I ask the students what they think will happen:
1. I take a bunch of holes from a paper punch and put them on top of the dome. Then I turn the machine on and the holes fly up into the air. The dome and paper, all having the same charge, repel each other. The paper holes spray up in a fountain of white dots.
2. I tape strips of paper to the dome. The paper stands up and stays standing until the dome is discharged. This is a good precursor to the hair thing. They don’t expect the paper to stay up in the air when the machine is off.
3. I use the grounding electrode to make the sparks jump really far. Let the generator run until you hear the ozone crackling. Then you get a great big spark. I use this to build some tension and fear of the generator because I’m asking for volunteers to do the hair thing.
4. Making hair stand up. The student needs to stand on a plastic milk crate or something to insulate them from the floor. One student wanted to try this standing on the ground. I think he had sweaty feet, he said (and we heard) the discharge going through his feet into the floor. I wish I could tell you how to know what kind of hair works best. Really long hair is too heavy, really short hair is too stiff. Hair color doesn’t seem to matter, although dark is easier to see than blond. For some reason, the hair of the black girls worked best. I’d love to post the pictures, but posting pictures of student’s is a no-no, at least without written permission.
5. Fluorescent light bulb lights up. It does not need to come into contact with the dome, the spark jumping to the glass with light up the bulb. We found that placing the bulb about 1 inch from the dome gave the best results. Stand on a piece of wood or you will feel the shocks in your toes.
6. We made a chain starting with one person charged up. He touched the next person, but held on. Now they both charged up and continued to another person. If the person getting shocked was sitting in one of our desk/chair units, he or she got a constant stream of shocks to the legs and back side.
7. Water bottle on top produces lightening like show. I’m going to tell you to be careful with this one. It works pretty well at first, but the massive sparking in the bottle actually burned through the bottom of the plastic bottle. Once they started leaking, they wouldn’t charge up. I had to use a different bottle for each class. More importantly, the bottle kept the charge. Just holding the bottle and moving it around gave a constant stream of rather painful shocks. At one point I was holding the grounding rod and the bottle. I touched where the bottle was leaking through the bottom and I got an extremely nasty jolt across one arm to the other. Be careful with this one.
8. A balloon placed near the dome is first attracted, then when it touches the dome, the charge is conducted and it is repelled. The charge leaks off and this repeats over and over again. I used this to lead into Coulomb’s Law and the force due to the electric charge. Again, you will want to stand on something to insulate you or you will have toe sparks.
Here are a few demonstrations that I haven’t yet tried:
- Mini pie tins stacked on top fly away one at a time – the pie tins I tried were too big.
- Soap bubbles are repelled as they get near the dome.