Day 30: Problems with Graphs

kin4 q

Physics 11  Question and solution from last day’s quiz on constant acceleration.  The students were really starting to push back on the graphing.  One student spent the weekend with his tutor and had memorized d = vit + 1/2 a t^2.  He used it, although he wasn’t sure why it worked.  Another student had been researching the use of graphs, and explained to the class that at least 3 other high schools in our district used equations to solve problems.

My response that plugging numbers into formulas wasn’t much to aspire to, nor would it benefit them in university or in life.  Apparently tutors also disagreed with this, saying that they have degrees and used formulas in university.  Another student claimed that he just didn’t like graphing. Of course the real problem is that he still doesn’t properly understand how to construct and read a graph, which leads to him not liking them.

So that’s where we are.  Despite of the pushback, the lesson plan for the day was to use a v-t graph to develop some kinematic equations.  Developing the equations has dubious pedagogical reasoning behind it, but I like the idea of showing that the kinematic equations don’t automagically appear out of nothingness.  I’m ok with this rationale.

Oh, the above question… Very few students were able to recognize that the area under the v-t curve was displacement.  They had been practicing this concept but mostly qualitatively. Placing the graphs in the context of a word problem shifted their perspective. I had expected this, we were only into our 2nd day of dealing with word problems.

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