Students took their energy assessment. For the first time, I had multiple students tell me the test was fun, which was especially good to hear since I included a free-response problem from the 2016 AP exam. My PLC has been focused on experimental design this year, and I’m enjoying seeing that payoff in my students not only doing well with that skill, but feeling confident enough that they can enjoy applying it.
Physical Science: Presentations
Students worked on presentations to make the case for their cargo carrier design. I gave students a template a colleague made last year to help students make sure they are connecting the science to their design, but, after watching them work, it feels like too much scaffolding. I made much better use of a graphic organizer for evidence-based reasoning than in the past and did more to embed that skill throughout the course, and I think framing the presentation as evidence-based reasoning on a bigger scale may have been enough. I need to think about what that might look like next year.
Students worked some problems using elastic vs. inelastic collisions. They are feeling very confident about energy, which is great to see, and several students are thinking about how they could use energy to work problems we’d done earlier in the year, which is fantastic.
As a side note, registration for our AP exams ends tomorrow, and I’ve offered doughnuts to the first class to get 100% registered. Its been surprisingly effective and I’ve currently got the highest registration rate. I need to remember to give the same challenge next year.
Physical Science: Testing Round 2
Students tested their second design. There was a nice variety of tests, including one group that had a tray of ice at the bottom of their ramp to simulate weather conditions. Most groups tried at least one collision besides the head-on we’d done before. One group asked if they could use bubble wrap to simulate a bumpy road. While the trucks are heavy enough that I don’t think the bubble wrap did much, I like the idea and am thinking about what might have worked better.
Since we only have four ramps, I assigned groups with similar tests to the same stations and directed them to figure out how they would share the equipment. It was more chaotic than the first round of testing, but that’s to be expected. I might scaffold them a little more on making that plan next year.
We whiteboarded the results of Friday’s Direct Measurement Videos to get to the definitions of elastic and inelastic collisions. A lot of groups tried to answer purely conceptually, in spite of some quantitative questions on the activity. I think these groups were treating each question as separate, rather than thinking about how one answer could help them with the next piece of the activity. I want to make better use of lab notebooks (most likely starting next year) as a reflective tool, which I think might help students see more connections between problems.
Physical Science: Building Again
Students worked on their second round of building. I upped the cost of paper cups, which were the most popular material on the first go around, which lead to a little more variety in egg holders. I also did another round of visiting each group and asking them to explain their design choices using Newton’s Laws, and I can tell students are getting more confident with this skill.
Students use a pair of Direct Measurement Videos, one of a collision between two billiard balls and one of a heavy disk tossed onto a cart, to explore changes in momentum and kinetic energy in the collisions. I haven’t done as much with uncertainty as I’d like, so I was very pleased with how clearly students were talking about it to decide if their values were “close enough.” I had students sketch momentum SOS and energy LOL diagrams, but students weren’t paying as much attention as I’d hoped to whether there were any dissipative forces present, so next year I want to do a better job of getting students into that habit. I was thrilled, however, when a student used some proportional reasoning to convince herself that you cannot conserve momentum and keep a constant kinetic energy when the objects are moving together after the collision. I was also pleased by how many students were interested in trying to explain the billiard ball that just spins in place right after the collision.
Physical Science: Test Design
Students began working on designing a second iteration of their cargo carriers. To encourage new designs, I increased the cost of paper cups (the most popular component on the first round) and shuffled groups. We also talked about the limits of testing just the front-end collisions, and tasked students with coming up with their own tests for this round. The discussion was a little trickier this year than in the past; we dramatically upgraded the trucks the cargo carrier attaches to this year and the old trucks would pretty reliably tip over or roll off the side of the ramp at least once per class, which gave a nice tangible example of the test’s limits. That didn’t happen at all this time, so next year I might take off the rails we put on the side of the ramps to try to encourage some failed tests.
Students whiteboarded CER statements for various energy questions, including their answers to where the bouncy ball loses energy and why the tiny bouncy ball from a seismic accelerator flies off. I really liked that different groups tended to take different approaches, which made for some good sharing of ideas once whiteboards were ready and made students very confident in their responses.
Physical Science: Crashes
Students attached their cargo carriers to trucks, then sent them down to ramps for head-on collisions. My students usually get pretty animated on this day, which usually includes a lot of bragging about how well they expect their design to do. For some reason, a lot of students in this class were expecting their eggs to break right away, including some students who were filled with confidence yesterday, and the class as a whole was very anxious and nervous. None of the points come from how well the design performs, so it was interesting to see how much tension some students were feeling, anyway.
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.
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!
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.
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.
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).
Students used a modified Atwood’s machine to collect data for a relationship between force and acceleration. We spent some time unpacking that statement since I’ve found it really isn’t obvious to students what that means; last year, a lot of students really struggled to go from that statement to recognizing they needed to change the force and measure acceleration,
Earth Science: Wind Turbine Wrap-Up
To conclude the wind turbine project, I gave students some information about an imaginary small farm and tasked them with selecting locations for three wind turbines and preparing a report for our “client” to justify their choice. Unfortunately, with the wind turbines and fans we have, it isn’t practical to set up both the topography and a trio of wind turbines for students to test their plans. Next year, I might try setting up a single, larger test area using a couple of our box fans so that we can have a big enough model for students to actually test their plan.
I showed students a video I made riding the elevator with a balance and asked them to determine whether the elevator was going up or going down and support their answer with free-body diagrams. I was pleased with how many groups started their conversation with “What’s our system?” I could tell from the conversations that a lot of students are still not entirely solid on the idea that an acceleration can be in the opposite direction of the motion, but thinking about the bowling ball lab from a few days ago seems to be helping. Next year, I want to do a better job of using the change in velocity arrows that show up in Etkina to help solidify the direction of acceleration.
Earth Science: Turbine Interference
In the next step towards designing a wind farm, students experimented with several turbines, comparing the amperage produced with different arrangements. This lab got my students asking some great questions that had me wishing that the trimester on physics came first rather than second this year. A lot wanted to know why the last turbine in a line wasn’t spinning, which is easy to explain with conservation of energy. A few others wanted to know what’s inside the turbine, which fits great with the build-a-motor lab we do in 9th grade physics. When we work on next year’s schedule, I’ll make sure to advocate for physics-earth-earth rather than this year’s earth-physics-earth sequence.