# Day 2: p vs. t Graphs, Graphing, & CER

AP Physics: p vs. t Graphs

This concept development sequence comes from conversations with Michael Lerner, Kelly O’Shea, and the rest of the Physics! PLC!

There was still some debate from yesterday about whether the bowling ball had a constant speed after a tap, so I pulled out the Motion Shot app to make a motion map. Afterwards, students did a variation on the bowling ball lab with combinations of taps to introduce momentum vs. time graphs. I picked a few scenarios to help them get the idea of negative values for force and momentum as well as some to get at the significance of a non-zero intercept on the graph.

Physics: Graphing

Students worked on their graph for the dowel lab, then we talked about “translating” the equation for the line of best fit by adding units and variables appropriate to the quantities they graphed. Students seemed to do well wrapping their heads around that step. Tomorrow, I’m going to have them write the slope as a statement a la Arons.

I’m also thinking about repeating the data collection tomorrow. Students are getting a wide range of slopes and intercepts and, if we’re going to take the time for a unit on experimental design and graphing, I’d like to establish careful practices right off the bat.

Next year, it could be interesting to mess with the calibration of the triple beam balances to give a non-zero intercept. I’m not sure yet if I would do that immediately, or if I would do a second round of data collection with the balances off.

Chemistry Essentials: CER

I put a CER at the end of yesterday’s lab, and students seemed pretty thrown by the reasoning piece. Today, I played the “My Dad’s an Alien” commercial and had students identify the kid’s claim and some of her evidence. Then, students got into their groups and had to fill in the reasoning for at least one piece of evidence. A lot of groups looked at why she might see something as evidence (like why the car seems like a spaceship), as well as why the evidence might support the claim. Yesterday, I felt like I was struggling to keep students on track, but today they were very engaged and even enthusiastic about the task. I think today I was much clearer about what they should be doing and what that looks like.