Lesson 3

3.1 and 3.2 worked most smoothly with 2 kids to a computer, if you have access to additional laptops. I added a box for explaining predictions above the graph in #7 and 10. I also asked students to get into the habit of labeling the axes of graphs like the computer printouts, both to make sure that they were differentiating between speed-time/position-time and because when I was working through #13 I found it much easier to have some units. Some kids had rationalizations like "The position graph is steeper when it is faster because it is going farther in a certain about of time." I asked all groups to show me their work when they got an initial idea for #13; I found many students misinterpreted this (because the actual question is above the graphs, not just where it actually says #13.), and just described the graphs instead of actually coming up with a rule that they could apply. They were able to do this well in the end, but it took a few check-ins. Rise over run came up frequently. I usually told students that was excellent, but also encouraged them to think about what rise would signify (what does it represent if it goes higher on the y-axis?).

I wonder if we could have a more clear-cut graph for #14 - I didn't see it causing problems with students, but when I did it it looks like it goes 100 m in 2 sec, or 50 m/s, while according to the data it is technically 40 m/s. This makes sense, because it just means my reading of the graph was off by 1/2 of a second, but it seems like if this is their first opportunity to check their strategy kids could think they've done it incorrectly. Probably not though - I haven't had that question come up yet.