Technology

Day 116: Circuit Sim & Mystery Tube

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AP Physics: Circuit Sim

Students used the PhET Circiut Construction Kit to start exploring circuits. Students had some great conversations around a few questions about the blue dots I took from the PUM curriculum. I was surprised to hear some students say the blue dots must get used up since batteries die over time, but students were able to test that idea by removing their battery. This lead a few students to connect back to momentum, thinking of the battery as a source of impulse, which I thought was an interesting connection.

circuit

Earth Science: Mystery Tubes

With the start of a new trimester, students got shuffled again. A little over 75% of my 9th graders haven’t had me yet this year, so I will need to make sure I am paying attention to classroom culture and helping students understand what I want from them.

To get students practicing observations and inferences, I had them play with the mystery tubes. In their notebooks, I asked students to explicitly connect each inference to at least one of their observations with an arrow. Several groups were surprised when I told them their sketch of the inside of the tube was a useful inference, so I know I’ll need to do some work with this group explicitly valuing non-verbal representations. Tomorrow, I’ll take some time to connect this activity to the scientific process and how I want to approach this course.

mystery tube.jpg

Day 108: Collision Types & Building Again

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AP Physics: Collision Types

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.

ap-wb

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.

eps-cx

Day 107: Collisions & Test Design

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AP Physics: Collisions

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.

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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.

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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 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.

9th

Day 92: Angular Momentum & Motion Graphs

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AP Physics: Angular Momentum

Students took a  quiz on conservation of momentum, then we finished yesterday’s discussion to introduce the idea of angular momentum. I showed them a Direct Measurement Video of two people on carts pushing off each other, followed by one of a rotating iPod to get a clear analogy for conservation of angular momentum. I think this would be worth taking the time to make a more student-centered discussion with students whiteboarding explanations next time around.ipod-rotates

Physical Science: Motion Graphs

Students used Vernier Video Physics to do some simple video analysis of a mini hover disk and start looking at position vs. time and velocity vs. time graphs. I had them stay in Video Physics to view the graphs, but students are struggling to make sense of their graphs for constant velocity with the auto scale. I’m debating how I want to change it for next year. I’m leaning towards spending 1-2 days doing constant velocity with a low-tech, breadcrumb approach. I’d probably have students calculate the speed over each interval to make a velocity vs. time graph. Then, we can switch over to video analysis for constant acceleration.

ramp

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).

engineers

Day 90: Angular Momentum & Mirror Mazes

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AP Physics: Angular Momentum

Students used a Linear and Rotational Collision Direct Measurement Video to get some practice with conservation of momentum. In the first question, I asked students to determine whether momentum was conserved in a certain collision using a calculation, and I was surprised by how many students struggled to understand the question. I might change up wording on some of the problems we did to explicitly have them state whether momentum is conserved or if there is an external force, similar to how I approach force problems by first asking students whether the forces are balanced.

I also asked some questions about whether momentum is conserved in collisions where the block starts to spin, and I heard some great conversations about uncertainty, external forces, and other big ideas that have me really looking forward to tomorrow’s discussion.

momentum-dmv

Physical Science: Mirror Mazes

Students used what they know about refection to solve some mirror mazes. I had some where students were given the placements of the mirrors and had to place the target and others where they were given the target’s location and had to place the mirrors. Since we haven’t done much with ray diagrams, this seemed to really solidify what I mean by the path of light.

obstacle

Day 76: Unbalanced Forces & Motors

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AP Physics: Unbalanced Forces

I borrowed an activity from my AP Summer Institute where students get a position vs. time graph and a velocity vs. time graph for a cart on a ramp. At the institute, we were tasked with finding the angle of the ramp and force of friction, but I decided to take a more conceptual approach and tasked students with writing an argument on whether friction is negligible. This was a little ambitious for their first experience with 2D unbalanced forces; I think it would have gone smoother if we’d spent some time practicing free-body diagrams and vector-addition diagrams for unbalanced 2D forces first.

cart-on-ramp

Physical Science: Motors

Students built electric motors, then did some simple experiments to drive home the connection between electric currents and magnetic fields. They seemed to get the connection between today’s lab, the electromagnet lab from Friday, and basic electricity generation.

I also took some time during class to talk with my students about what I want from them during a post-lab discussion and what I’m trying to accomplish during those discussions. I saw a lot more students participating in today’s discussion, both by raising their hands and by adding to their notebook entries. I’m planning to keep reminding them of what the post-lab time should look like, as well as share a little more about why I do things differently than the other 9th grade teachers. I need to remind myself that even if I’ve been in this routine for a full trimester, this is still new to most of my students.

 

Day 70: Hoop Practical & Circuits

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AP Physics: Hoop Practical

We finished up a lab practical on angled projectiles. Each group had a different distance from the launcher and figured out how high above the ground to place a hoop. In both classes, some groups had to shift their hoop to one side or the other, but eventually managed to get the projectile though all the hoops. I also had some goal-less problems to try and shift students away from needing to be able to picture the full solution to be able to progress. The problems mostly got ignored, because it was more exciting to watch the parabola of hoops come together and it took most of the hour to get all the hoops in place.practical

Physical Science: Series vs. Parallel Circuits

Students used the PhET circuit construction kit again, this time using a lab on series and parallel I modified from Eugenia Etkina’s PUM curriculum. I think students  were getting the big ideas, but its very tough to circulate with a full class in the computer lab, so I feel a little blind. Last year, I was able to do the PhET sims on netbooks in the classroom, so it was easy for me to listen i on student conversations and pull them together at the end of the hour to discuss some big ideas. Next year, I might re-work my calendar to make time for a day in the classroom so my students and I have a chance to make sure they are on track.

circuit