Instructional Strategies

Day 105: Dissipated Energy & Building

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AP Physics: Dissipated Energy

Students analyzed video of their bouncy balls and collected evidence to argue whether the energy is primarily dissipated by air resistance or by the impact with the table. There was a nice variety of approaches and I was pleased by how many students went back to the fact that we neglected air resistance during projectile motion to make a prediction about whether it should matter here.

pos-time-graph

Physical Science: Building

Students worked on building their cargo carriers based on yesterday’s designs. To help keep the focus on the science behind their designs, I stopped by each group and used a dice to pick someone to tell me how Newton’s Laws support their design decisions. For the first time, I had several tables where students were hoping they would be the one picked because they were excited to talk about their group’s work, which was fantastic!

carrier

Day 104: Missing Energy & Designs

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AP Physics: Missing Energy

After watching a bouncy ball to see it loses mechanical energy, I tasked students with determining whether the energy is mostly dissipated during an impact with the table or mostly dissipated by air resistance. Today, they recorded video of the bouncy ball, then whiteboarded some representations for each explanation to get ideas about what could make good evidence. This is the first year I’ve done this activity where almost no groups think air resistance is the biggest factor. Students had a lot of great dialogue about forces and the motion of the bouncy ball as they worked on the representations.

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Physical Science: First-Round Designs

Students worked on their first design for a cargo carrier that will protect an egg in a head-on crash. I don’t want this project to become just building, so I had students fill in a graphic organizer version of a CER, replacing the claim with their design idea and using the evidence and reasoning to explain why they think their idea will work. Tomorrow, I’ll help them make those explanations deeper by talking to each group while they build.

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Day 103: Energy Practical & Explanations

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AP Physics: Energy Practical

I tried a new lab practical for energy in an effort to integrate rotation and spiral back to some old ideas. Back in December, students measured the launch velocity of a marble, then predicted where it would hit the floor. Today, I had them use conservation of energy, including rotational kinetic energy, to find the launch velocity of their marble, then predict where it would hit the floor. I saw a lot of students pull out their old work, including their lab from December, to help remind themselves how to do the projectile portion of the problem, which is exactly what I hoped they would do. I overheard several students talking about how much they liked looking at an old problem through a new lens, as well as seeing how old ideas fit with the new ones.

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Physical Science: Explanations

Students practiced making predictions and writing explanations using Newton’s Laws. I showed students some videos and clips, including one from Smarter Every Day and an animation of the Mars Pathfinder landing, then had them write an explanation individually, followed by a revised explanation with their whole group. I was struggling more than usual to keep my students focused, but part of the problem might have been the English test next hour and the pep fest this afternoon. I’ve got some demos I’m planning to have students write explanations of as warm-ups, and I probably would have been better off using the demos today, then using the videos as warm-ups.

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Day 102: Gallery Walk & 2nd Law

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AP Physics: Gallery Walk

I ended up having students do a gallery walk for yesterday’s problems.

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Physical Science: Newton’s 2nd Law

Students worked on a version of the modified Atwood’s machine lab for Newton’s 2nd Law. While I have students make a graph, we don’t go much deeper than whether each relationship is direct or indirect. I spent more time on the pre-lab discussion today than I have for most labs with this group, and I feel like that paid off with more confidence while they were actually working in the lab.

n2l

Day 98: Mistakes Game & Motion Detector Lab

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AP Physics: Mistakes Game

Students played the mistakes game with energy bar charts. My 2nd hour had a sub, so I’m not sure how things went. My meeting got done early, so I made it in time for my 4th hour class. This group is usually quieter during discussions, and they were much more nervous about doing the mistakes game without me since they were not confident they would get the right answers, but I was able to sit back while my students ran the show.

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Physical Science: Motion Detector Lab

Students worked on describing motion based on position vs. time graphs. On Monday, we’ll get out the motion detector to check their descriptions. They had a sub, so I’ll find out then how things went.

Day 97: Energy & Free Fall

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AP Physics: Energy

We had a board meeting on the two energy labs from this week. The kinetic energy groups tended to get very nice results; I had them check their model with multiple cart masses and ramp angles, and they saw the results were consistent. I had the elastic energy groups use multiple springs, but they didn’t see as clear a difference between the slopes as I would have liked. I’m wondering if the results would be less muddy if I had them plot gravitational potential energy on one axis rather than just plotting height. I shortchanged some of the pre-lab discussion, and I think that lead to students forgetting to do things like measure the cart’s starting height or measure both the starting and ending height from the same end of the cart.
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Physical Science: Free Fall

I got out washers, manila folders, and a few other things and tasked students with determining what affects the time an object takes to fall. In the pre-lab discussion, a student suggested the fluid an object falls through could affect the time, so next year I might make sure I have graduated cylinders and some different liquids available. I offered to grab materials if a group wanted to try that, but I think asking me to get stuff felt like an extra hurdle.

free-fall

Day 95: More Energy & Sledding Problem

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AP Physics: More Energy

I split the class in half with some groups doing a lab for elastic energy and others doing a lab for kinetic energy. The groups looking at elastic energy looked for a relationship between how much a spring launcher is compressed and the maximum height above the table the launched cart reaches. The groups doing kinetic energy looked for a relationship between the starting height of a cart above the table and the speed at the bottom of the track.

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Physical Science: Sledding Problem

I gave students two position vs. time graphs that I said describe two people sledding, and had them do some interpretation. Students started by describing the motion of each sledder, then identifying where they collided. Finally, each group prepared a CER for who’s fault the collision is, which we then used for a short philosophical chairs where students made their case to the rest of the class. This lead nicely into a brief discussion of assumptions and they role they play in generating an explanation or a claim in science.

The sledding story made the coordinate system tricky for students. I wish I’d spent time discussing the descriptions of the motion so we could make sense of them moving in opposite directions.

sledding-graphs

Day 94: Intro to Energy & Motion Graphs

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AP Physics: Intro to Energy

Students picked a height to raise their cart above the table, then made a rough force vs. displacement graph and repeated for additional angles. We compared the areas of the graphs, then defined that area as the change in gravitational potential energy. The biggest hangup is that students are so used to graphing their data that I have trouble getting across that I want a description of an individual run, instead. I might try some additional discussion prior to the lab next time.

As a side note, it was interesting to watch what looked like some gender dynamics in one of my classes. All but one of my all-male groups picked a fairly high point to raise their carts to, then used very steep angles, getting their tracks nearly vertical. The one all-female group in the class picked the lowest point they could, then did very shallow angles. I also had one mixed-gender group, and they picked both a height and angles right in the middle.

 

Physical Science: Motion Graphs

We finished whiteboarding results from the video analysis, following each up with a similar case on the motion detector. I should have broken up the discussion a bit more, which reinforces what I was already thinking about with going low-tech for constant velocity, then introducing video for constant acceleration. I also had students move away from their lab tables for the group discussion, and talked a bit about why I was doing it, and students were much more focused on the whole-class discussion this time.

Day 93: Whiteboards & More Whiteboards

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AP Physics: Whiteboarding Angular Momentum

Thanks to a reminder from Dan Burns, I kicked class off with a clip from The Simpsons where Principal Skinner uses conservation of angular momentum to save Ralph. Afterwards, students whiteboarded and discussed yesterday’s problems. I focused on the conceptual problems, and I was pleased by how many students opted to use tools like SOS diagrams to guide their thinking, whether or not the problems asked for them. I also had some groups use analogies to linear momentum to answer questions since they found it easier to visualize. I got really excited when a couple of groups used Newton’s 3rd Law to solve one of the problems, though I didn’t think to take a photo of their boards.12th.jpg

Physical Science: Whiteboarding Motion Graphs

Students whiteboarded their video analysis results for constant velocity. This was the first time I’ve had them talking about graphs, and they made a lot of great observations. After the discussion, we used Logger Pro to look at a constant speed buggy in front of a motion detector and refine some some of the things we saw in the video analysis; after seeing me change the axes on the v vs. t graph from the motion detector, most groups looked at the scale on their v vs. t graphs and decided they should be horizontal lines. It was also fun to see the expressions on some faces when I found the slope of the buggy’s x vs. t graph and they saw it was the speed.

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Day 91: Whiteboarding & Engineering

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AP Physics: Whiteboarding

Students whiteboarded some problems from Friday and yesterday’s Direct Measurement Video. There was some good discussion about a problem about a collision between a Hummer and a VW Bug, comparing the force, the change in momentum, and the acceleration of each. A lot of students did some really good wrestling with the conceptual distinctions between those ideas. There was also some good discussion about whether momentum is conserved when an object starts rotating. All the groups that said rotation takes some momentum had a calculation, while the groups who said rotation does not impact conservation of momentum used a few different approaches, which gave a nice opportunity to talk not only about uncertainty, but the value of multiple lines of evidence.

Physical Science: Engineering

I decided to expand the big engineering project we have this trimester to include both motion and forces, so today we introduced the project. We spent some time talking about what engineers do, and I was very excited that collaborate was the first thing a student mentioned. We also did some problem scoping, where I gave students a fictitious memo from our “client” and had them use the information to describe the problem, the criteria for success, and the constraints we’ll have to work within, as well as start brainstorming some of the science knowledge they will need for the project. I’ve tended to skip problem scoping, since a fake client feels cheesy to me, but it was interesting to see students really analyze the fairly short text of the memo; it was also interesting that students are thinking about the constraints as reasonable client requests instead of arbitrary obstacles I imposed (at least for now).

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