Gasses

Day 73: Multiple Choice, Forces, & Gas Laws

/ Marta R. Stoeckel / 1 Comment

AP Physics: Multiple Choice

After a quiz on projectile motion graphs, we spent some time using Plickers to practice multiple choice on energy and projectiles. One of my classes pretty openly started guessing, rather than thinking about the problems, so I think we may be doing multiple choice a little too regularly. I may start either alternating each week between relevant multiple choice and free response or just use quiz days for explicit AP practice less often.

Physics: Forces

Before today’s quiz, students whiteboarded their diagrams for the problems earlier this week. Pretty consistently at this point, the students who take the time to get their diagrams right do fine on the calculations, which is not surprising. Getting students to put units in their work is still a challenge, but I saw a lot more confidence from my students today than I have in a while.

forces wb.jpg

Chemistry Essentials: Gas Laws

Before today’s quiz, we did a quick debrief of yesterday’s lab on the gas laws. Since the ice water didn’t work well yesterday, I tried putting them outside (the air temperature was -10 degrees F today!), but still didn’t see much change, so I think the syringes I have just don’t seal well enough. We’ll finish the post-lab discussion on Monday.

Maker:S,Date:2017-10-21,Ver:6,Lens:Kan03,Act:Lar02,E-ve

Day 72: Projectiles, Forces Practical, & Qualitative Gas Laws

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AP Physics: Projectiles

We worked through some problems I got from Michael Lerner where students apply other models from this year so far to an object dropped straight down and I was pleased with the connections students were making. I also asked students to predict what should happen to the time if the object were heavier and if it were launched horizontally, and got some great discussion. We wrapped up by trying each and checking the results with slow-motion video.

 

Physics: Forces Practical

Students wrapped up the forces practical from yesterday. I scaffolded the practical more than usual by breaking it into small steps, asking students for each representation and several calculations along the way. Several students commented that was very helpful when they took another look at the problems from earlier this week.

Chemistry Essentials: Qualitative Gas Laws

I got out the syringes for students to make some qualitative observations about the ideal gas laws. The ice water baths didn’t produce much change for the groups I was able to talk to today. With this class, I’m spending more time redirecting students or dealing with groups damaging lab equipment than I am talking to students about chemistry, so I need to think about how to shift that. There is a para who is going to work on helping to keep students on task. I also need to remember the instructional coaches have offered to help manage things on lab days.

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Classroom Display

Earlier this week, I put up a “Scientists can be…” display inspired by Liz Mastalio. Its been a lot of fun listening to students react to it; some are looking for which ones they don’t know while others are clearly drawn to specific identities. My AP students have been telling me who they’d like to see up there, so I want to open the door for them to submit a poster with a label. That could help me get some identities I missed that matter to my students.

Maker:S,Date:2017-10-21,Ver:6,Lens:Kan03,Act:Lar02,E-ve

Day 26: CoM Board Meeting, Breaking Down Problems, & Gas Laws

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AP Physics: Center of Mass Board Meeting

We had a board meeting to discuss the results of the video analysis from the last few days. I asked students to write a CER for whether the forces on each system of pucks were balanced or unbalanced. This lead nicely into some conversation about what exactly we mean by the two -puck system. I ended up wishing students had more experience interpreting position vs. time graphs prior to this discussion; we’ve mostly worked with velocity vs. time graphs so far, and the various uncertainties piled up to make it look like the velocity was changing. The position vs. time graphs were much more convincing, but students weren’t as likely to look at those.

Afterwards, we played with the coupled carts from Kaar, Pollack, Lerner, and Engles’ The Physics Teacher article. The graphs were very satisfying.

Top: v vs. t for each cart, Bottom: p vs. t for system

Physics: Breaking Down Problems

On the last quiz, a lot of students really struggled to interpret the problems, so we spent some time today on how to break down a physics problem. As we discussed how to approach a problem, we took time for students to apply each step to the problems on the most recent quiz.

quiz tips

Chemistry Essentials: Gas Laws

We used the results of yesterday’s simulation to develop the gas laws. I’ve found a lot of my students really struggle with algebra, so, rather than developing equations, we came up with statements using proportional reasoning which students then applied to some problems. Some of my students who really struggled to manipulate the density equation were very successful with today’s gas laws problems, so I think this approach was a success.

Day 25: Center of Mass, Board Meeting, & Gas Laws

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AP Physics: Center of Mass

Students continued yesterday’s video analysis, based on the article by Taylor Kaar, Linda Pollack, Michael Lerner, and Robert Engles in The Physics Teacher. Today, students analyzed the motion of four hover disks linked into a square from several different perspectives. They were a little bothered that it was tricky to spot the center of the square, but I like that we’ll be able to have a conversation about whether there has to be any mass at the center of mass.

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Physics: Board Meeting

Students whiteboarded their results from the video analysis the last few days. Framing this around a CER with a more specific question than usual had the desired effect and I saw students keeping much more complete records than usual. Students are continuing to struggle with recognizing the physical meaning of features on the graph, so I need to keep giving students opportunities to work on that.

phys cer

Chemistry Essentials: Gas Laws Simulation

Students used the PhET Gas Properties simulation to take quantitative data for the ideal gas laws. I think the class would have benefited from a little more discussion prior to using the simulation to set up what we were measuring and why, rather than just giving them an assignment in Google Classroom that told them what to measure. However, students were very successful in recognizing the quantitative relationships I wanted them to see.

Gas Laws Sim.PNG

Day 24: Center of Mass, Ramps, & Gas Laws

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AP Physics: Center of Mass

Students started a video analysis activity by Taylor Kaar, Linda Pollack, Michael Lerner, and Robert Engles that recently appeared in The Physics Teacher. I gave students a video of two linked hover disks and had students first track one of the disks, then track the center of mass for the system. In their article, the authors say their students resist tracking the disks, wanting to jump straight to the center of mass. My students, however, were very happy to track the motion of the disks, which made for a really satisfying payoff when they saw how much simpler the motion of the center of mass is.

Linked hover disks; from video by Kaar, Pollack, Lerner, & Engles
x vs. t for disk (red) and CoM (green)

Physics: Ramps

I’ve found a lot of groups are recording pretty incomplete data during labs. I think since groups don’t make much use of their individual results, some of these students aren’t seeing the value in recording that information. To give them a little more purpose, today we had some discussion to identify changes that could affect the motion of a hover disk on a ramp, then tasked them with collecting data to write a CER to answer how the change affects the motion. This will hit some points I wanted to get anyway, while also giving each group their own task using their data.

ramp hover

Chemistry Essentials: Gas Laws

Students made qualitative observations using sealed syringes in water baths. The ice machine in the school is broken, so the cold water tests didn’t work out very well, but we got some great results with hot water. A few groups had some trouble distinguishing between a change in pressure and a change in volume, so I wish we’d spent some time discussing how we could tell when the pressure in the syringe went up prior to the lab. However, by the end of the hour, groups were able to come up with qualitative descriptions of the ideal gas laws.

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Day 20: Force Diagrams, v-t Graphs, & Diffusion

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AP Physics: Force Diagrams

We went over the force problems from last week. I skipped having them whiteboard all of the trig and algebra, and just had students whiteboard the diagrams and some selected reasoning. There was some good debate on whether the normal force should equal gravity on some of the problems, and the vector addition diagrams were a great tool for reasoning that through.

vad wb

Physics: v-t Graphs

Students whiteboarded their solutions to Friday’s constant velocity problems. The problems were a lot more challenging than I expected. One big struggle for a lot of groups was making sense of what the problem was asking. The other big struggle was connecting strategies and ideas from one problem to the next one. For example, after using the area of a velocity vs. time graph to find displacement on the first problem, many students struggled to find the displacement from a v-t graph on the second problem. This tells me students were following a procedure without understanding why, so I need to think about how to step back and get that idea across.

vt wb

Chemistry Essentials: Diffusion

Students whiteboarded particle diagrams for perfume dispersing through the classroom and food coloring dispersing through water. In both cases, students made a lot of great observations prior to whiteboarding and had a lot of good foundation on their whiteboards.

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