I just wrote this up over at the home.drewsday blog, but the real reason for taking the photos was to use this in class next quarter. We start with thermodynamics; one of the first topics is thermal expansion and contraction.
I regularly read Dan Meyer's blog. He was (is?) a math teacher, but I'm consistently inspired by his ideas. One of his regular features is something he calls "What can you do with this?" [WCYDWT]. The idea is that he finds an example of something in the world which illustrates a math concept and brings it into the classroom.
When I saw the contraction of the vinyl siding on my house, I knew I could bring it into the class next quarter. The question is: What can you do with it?
I want to present this to class, so I have to think of the questions that would be appropriate. Usually, when I start a problem in class I make a list of everything I know and everything I don't know (or want to know).
What I know
- temperature outside today was 12° F. (
- nominal length of the siding was 12 feet. (
- change of length (on one side) was 1/8 inch. (
- temperature when the siding was painted (
- coefficient of linear expansion for the vinyl siding (
I have no idea what the temperature was when the house was painted. I didn't even know the house existed when it was painted. I suppose I could come up with a reasonable estimate, but realistically, there is a pretty wide range of temperatures to work with. Conservatively, I would guess that the painting could have been done when the siding was anywhere between 60° F and 90° F. That is a pretty wide range, so I'm not sure I want to try to estimate that and use it to find
° C, which is 74.5° F. (Right in the middle of my estimated range, hmmm...)