# Monthly Archives: July 2014

## [3 Acts] The Coefficient of Friction of My Son

Last year in Physics, I used the PhET simulation Ramp: Forces and Motion to teach about calculating the coefficient of friction in the situation of an object on a ramp (in this case, a box).

This has worked well enough for me in the past. However, as I was travelling home with my son, I had an idea to create a 3 act lesson using my experiences.

Perhaps I talked too much in the video, so I might just show them the final part where I’m sitting up with Benji.

The idea really did just hit me as I was sitting there in the train, thankful that I didn’t have to keep my arm under him, propping him up. So often, ideas will come to me, but I’m just not in the right location to jot them down to save for later.

Another thing I thought of pertaining to this lesson is how it relates better to the girls in my class than most of the lessons. Sure, some girls like talking about drag racing or shooting a basketball, but this connects better to the majority of girls than those other lessons[1].

One downside to this activity is that on the train & plane, I’m not concerned about the coefficient of friction–I’m concerned about what angle I can sit up with him without him falling down. And that’s what we’re measuring at the start, so finding the coefficient of friction has become a superfluous academic exercise despite the “real-world-ness” of the problem.

And then there are the other things that I hope students will consider: things like my chest isn’t actually flat and we both have shirts on, so I guess we’re actually finding the coefficient of friction between his shirt and my shirt. But those are great things for students to consider on their own, so I don’t want to spoil it by pointing out all the inconsistencies in the video from the start.

[1] If you think I’m being sexist here, you should try walking down an airport terminal with a 3-week old. At least 10 times more women than men will stop you and say something.