# Day 73: Problems, Work, & Gas Laws

Today was our first day back from break.

AP Physics 1: Problems

Students worked on some conservation of energy problems. I had to do some prodding to remind students to start with an LOL diagram, but they got into the swing of things fairly quickly.

Physics: Work

Students sketched force vs. distance graphs for raising a cart to the same height using different ramps in order to introduce the idea of work. Results were a little messier than usual, but I think I didn’t introduce the lab as clearly as usual and my students weren’t as focused as usual thanks to it being the first day back from break. But, we were still able to get the ideas we needed.

Chemistry Essentials: Gas Laws

Students made some observations with capped syringes to get a conceptual understanding of gas laws. After a hot glue fail last tri, I glued the caps on with super glue, and the lab worked very nicely. It was really tough for a lot of students to connect their observations to particle diagrams, so I think it would have been worth spending a little more time before the lab revisiting what particle diagrams show.

# Day 27: Collisions, Graph Stacks, & Linked Balloons

AP Physics: Collisions

Students started collecting data for the momentum before and after a series of different collisions to discover conservation of momentum. Several groups had a lot of trouble with what we meant by before or after the collision, which showed up as trouble both in filling out the table I gave them and in seeing how to place the carts and photogates appropriately. I wonder if having students draw an SOS diagram for the first collision would have helped with that.

Physics: Graph Stacks

We used the motion encoder to check the graphs students drew for objects on ramps earlier this week. Afterward, students started working on translating between our different representations for accelerated motion. A lot of my conversations with students today have me thinking that many of them are memorizing shapes of graphs without understanding what they represent. I need to keep working on ways to help students attach meaning to the shapes.

Chemistry Essentials: Pressure

I put a large balloon and a small one on opposite ends of a PVC pipe, using alligator clips to close both. Students sketched particle diagrams to predict what should happen when I removed the clips; I wish I’d had them write CERs instead to encourage more interpretation of the particle diagrams. After I showed students both balloons stays the same size, I had them do a second round of particle diagrams to explain why. There was some great conversation about pressure, but I think that phase also would have been better served with a CER.

# Day 23: Elevators, Board Meeting, & Pressure

AP Physics: Elevators

I took some time today to introduce students to the CER framework. I showed them a force vs. time graph I made by riding the elevator with a mass hanging on a force sensor, then asked them to determine whether I was riding the elevator up or down. We haven’t done much with unbalanced forces yet, but they were pretty successful determining which direction I rode it.

Physics: Board Meeting

Students whiteboarded sketches of their graphs from yesterday. Its been taking longer and longer for groups to prepare whiteboards, so I think I will try setting a time on the SMARTBoard to try and speed things up. I also found a lot of groups were missing information we’d discussed recording prior to the lab yesterday, so I think we need to revisit lab notebook practices. The discussion was very abbreviated, so we only got a chance to discuss a little about the position vs. time graphs, but students were able to recognize the key ideas. On Monday, we’ll talk about the v-t graphs and look at some variations.

Chemistry Essentials: Pressure

To introduce pressure, students watched a balloon in a vacuum chamber, then whiteboarded what they thought was happening. Students were pretty successful at coming up with useful ideas to explain what they saw and inventing the idea of pressure.

Afterward, we boiled water in the vacuum chamber. We ran out of time to whiteboard it, but, on a whim, I got out my thermal camera and recorded a video to show the water stays cool.