Today at the end of Lesson 2, I started seeing that students' interpretations of the position-time graphs (and also their copying of the graphs from the Logger Pro application) was incomplete.
There were two ways they graphed these two graphs - I've drawn them crudely below:
The top graph is often interpreted by students as the red line is the faster motion and the black line is the slower motion rather than that they are both approximately traveling at the same constant speed. About half the class had a graph that looked like the top graph.
We agreed that the flat spots on the position-time graphs represented no motion, so then we just compared the first part of the motion for each of the two graphs that students reported.
I had a student collect and "store latest run" up in front of the class (projected on the SmartBoard) so that we could show the class the motion on the same graph. I then had students talk with their table group about which of the two graphs to the left best matched the data we collected up front. There was agreeement that the graph that best matched the motion up front was the second graph. Students were then instructed to make sure their understanding was written in their idea journal.
Also, watch for students who want to start these graphs at 0,0. That's not what the computer shows.
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