Archive for May 2008
This is much harder to write than to show. The physics books usually have a problem about the tension in a horizontal cloths line with a single force hanging down in the middle. We can calculate these forces fairly easily, but hands on is better. The outdoor demonstration is to tie a strong rope between a tree and a car, then moving the car by applying a perpendicular force on the rope at the midpoint.
There is an even more effective demonstration of this that can be done in the classroom. It’s a martial arts escape from two attackers. I like to pick the two strongest and largest students as my victims. They each grab one of my wrists and pull away from each other. (They think they are so tough.) I then take a big step backwards and pull my hands towards each other. The two attackers move towards each other with a great deal of force and almost always bump into each other with surprising speed and force.
Mythbusters & The Scientific Method
Posted on: May 31, 2008
- In: Projects
- 31 Comments
The popular show Mythbusters is a terrific example of the application of the scientific method. Early in the school year I introduce the scientific method. I then hand my class a worksheet that they fill in as they watch one of the episodes I have on DVD. They have to identify the hypothesis, controls, variables, experimental steps, and conclusion. mythbusters-and-the-scientific-method
Next, the student choose to work as an individual or in a small group (2 or 3) and they work on coming up with a myth they are going to bust. Now, you and I know this is just a mini-science fair project, but they don’t see it that way. My students were just telling me that this was their favorite project of the year. Good thing I didn’t call it a science fair project. Anyway, I let them do whatever they want so long as they are doing good science and they are not doing something dangerous. When there were a few that were dangerous, I discussed the project with their parents to make sure they were aware of what their kids were doing.
I teach in Philadelphia at a Charter School and the students come from all over the city. It is very challenging for many of them to work together outside of school, so I have to allocate class time for them to do their project. I think I give them 4 days over a period of 2 weeks to experiment, work on their poster, etc. I’ve attached the guidelines and worksheet I use for them to document their project. I make sure they have thought through the controls and variables before they begin any experiments. mythbusters-project-guidelines and mythbusters-worksheet
The grading rubric needs a rework, but I included it as a starting point. mythbuster-rubric
I have the students do the project on regular poster board. I do this early in the year and then hang the posters on my wall as they are completed. They like looking at each other’s ideas and projects, and they like picking them apart, explaining how they would do the experiment differently.
Matchstick Rockets
Posted on: May 29, 2008
This is a favorite of the students. After studying Newton’s Laws of motion, we spend a day making rockets from paper match sticks. The process is simple, tear out a paper match, cover the top with a small piece of tightly wrapped aluminum foil, heat the match with a lighter and watch it launch.
Students will typically make at least three of these in a class period. Most go no more than an inch or two, many doing that backwards. Last year one match went 26 feet. This year, I believe the record was 18 feet. Credit goes to Richard White for sending me this last year.
The directions call for making the exhaust tube with a paperclip. That hasn’t worked well for us, the hole is too big. I’ve seen other directions that use a pin. I haven’t tried it with a pin, but I’d like to. In class, we simply wrap the tip tight and count on the gases finding their own exit.
Note: This is an outside activity unless you have a really well ventilated lab, which I don’t. Also, spend $5 on a BernzOmatic lighter. You can get it from Walmart. Aim for a day with very little wind otherwise you will have a hard time keeping the rockets on their launcher and even harder time getting them lit.
Rube Goldberg Project
Posted on: May 29, 2008
We just finished this project today. It makes me nuts, but I like the results. My room looks like a junkyard for almost a month. You have to be able to live with chaos or don’t try this in school.
If you are familiar with the game “Mousetrap” then you get the idea of the project. This year, I let the students choose their groups, they made up teams of four or five students. With twenty groups in all, they set out to create their own ten step project.
It seems easy, but it is more challenging than it first appears. The students had about three weeks of class time to try to make these work. They bring in old toys, dollar store junk, and anything they can find to create their project. It culminates with a full day of setting up and presenting their projects to the rest of the school.
The link below is a shortened version of one of the videos I use to introduce the topic. This is the Mythbusters Christmas special. In the full length version (I recommend that one over the linked file), they take quite a few attempts for them to make it work all the way through, and they do this kind of stuff for a living. http://www.youtube.com/watch?v=lCYg_gz4fDo
Some helpful documents for your use: Rube Goldberg Rules score-sheet-rev-c (5/29/09 – I’ve updated the scoring rubric to include a minimum time for the machine to run)
Also, if you Google “rube goldberg” you will get an endless supply of videos, including a large number of Japanese projects with an odd and addictive little ditty. I’d like to know what the little flags say, can someone translate?
Physics & Physical Science Demos, Labs, & Projects for High School Teachers 
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