Author: Marta R. Stoeckel

Day 47: Torque & Spectra

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AP Physics: Torque

Students started the classic lever lab to start building some ideas about torque, though we haven’t used the term yet. Today, I had them work on a relationship between the forces on either side of the lever, and encouraged different groups to use different distances from the fulcrum.

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Earth Science: Spectra

To introduce why spectroscopes are useful in astronomy, students played with diffraction gratings. We started by looking at some of the regular light sources in the classroom, and they were quick to come up with interesting observations and ideas to explain their observations. Then, we shifted to observing gas lamps. We only have one power supply, so we did those observations as a whole class. Then, in their lab groups, I had students look for patterns in where colors appear to get the idea that the same color always has the same distance, then to try to identify the gasses we’d observed.

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Day 46: Mistakes Game & Reflecting Telescopes

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AP Physics: Mistakes Game

We played Kelly O’Shea’s Mistakes Game using some problems with a central net force. Its great to see my students getting more skilled at discussing physics, which means I’m doing very little to keep the conversation moving. We had some particularly good discussions about a problem about the forces on a roller coaster car as it goes over a hill and about the forces on a yo-yo as it swings in a vertical circle.

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A whiteboard for the roller coaster problem

Earth Science: Reflecting Telescopes

Students played with curved mirrors to get some ideas about how mirrors are used in telescopes. I also got out some electric candles and tasked students with projecting the candle on a sheet of paper. They struggled with that step, but it was great to see their reactions when they got a nice, sharp image of the candle “flame”.

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Day 45: Central Force Problems & Historical Astronomy

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AP Physics: Central Force Problems

Students worked on a few problems related to central net force causing circular motion. I also introduced Newton’s Law of Universal Gravitation as we discussed a problem about orbits. A couple students got really excited when they realized the connection between Universal Gravitation and Fg = mg; one student decided that called for a dab.

Earth Science: Historical Astronomy

After the quiz on the Moon and planets, I did some short notes on historical astronomy. As part of the effort to incorporate engineering into 9th grade science, the curriculum calls for focusing on the tools astronomers use, but this seems like a great opportunity to incorporate the contributions of diverse groups. Next year, I want to do a better job of balancing the tools with the range of cultures we could talk about. I also want to find ways to make this lesson more active, but need to figure out what I can have students do without making the lesson significantly longer.

Day 44: Central Forces & Orbit Wrap-Up

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AP Physics: Central Forces

Students whiteboarded their results from Monday’s activity. In the computer lab, there was a lot of debate about what forces were acting on the weight, so I had students include an FBD for the weight on their whiteboards, which lead to some fantastic discussion in my second hour. Students had strong opinions on whether or not there should be a force to balance the tension and were quick to offer an argument one way or another. Even better, a number of students who are usually quiet during whole-class discussions put ideas and arguments out there. Along the way, students connected this back to the bowling ball lab, where one of their tasks was to get the bowling ball to travel in a circle using a rubber mallet. This was the first time I really felt like I got to just sit and listen while my students figured out something important together, and it was fantastic. As the class came to a consensus, one student captured his take with the “mind blown” gesture and sound effect.img_2473

Earth Science: Orbit Wrap-Up

Students took a few minutes for students to finish their measurements for the look at the orbit of Halley’s Comet, and we discussed the results. Interestingly, when we looked at the total distance to the focal points, the class averages for Halley’s Comet was better than the class averages for Mars. When I played with the data on my prep, I saw that one group got dramatically different results from the rest of the class. Tomorrow, I’d like to take some time to look at that with my students to get at the idea of outliers and how to handle them in science.

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Day 43: Assessment Reflection & Movie

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I was chaperoning a field trip today, so no photos and lessons that were easy to leave for a sub.

AP Physics: Assessment Reflection

Students took a test combining forces and constant acceleration today. On tests and quizzes, I’ve been asking students to rate themselves on each learning target and write a short reflection, so I took a few minutes to read over the reflections after the field trip. I like getting a sense of where my students feel confident and where they are struggling before I grade the whole test. It was also fun to see what students wrote. I’ve been trying to improve how explicit I am about what is included in a given model, so I was really pleased to see several students tell me that they started each problem by identifying what models apply, then thinking of the “toolbox” that goes with that model. I also was really excited to see a student who has been struggling write that, moving forward, he wants to shift from trying to understand what they answer is to trying to understand why its the answer.

Earth Science: Movie

The earth science curriculum calls for another movie this unit (I think I’ve shown more movies in Earth Science this year than I’ve shown in physics the last several years combined), and I went with it since that’s an easy thing for a sub. I’ve been using the existing worksheets to go with the movies, which have very factual questions in the order they appear in the movie. The next time I show a video, I might try getting the students to do a little more thinking by adapting some reading response techniques like four square notes or a 3-2-1 response.

Day 42: Mass & Comet Orbits

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AP Physics: Mass

Students finished the lab practical we started on Thursday where they used a modified Atwood’s machine to find an unknown mass. Today, once they had an answer, we checked their result using a spring scale. One of my goals this year is to work on hearing from every student, so I tried posting three questions about the lab (one for each group member). Then, before groups could check their result, I would roll dice to decide which group member had to answer each question. Since there are three students in each group, I was able to hear from every student. Groups did a really nice job of making sure all three group members could answer all three questions, which is exactly what I hoped would happen.

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Earth Science: Comet Orbits

Students finished up yesterday’s lab contrasting Mars’ orbit with Halley’s Comet’s orbit. A lot of groups were surprised when they realized that the patterns from Kepler’s Laws worked equally well for both orbits, especially when they used mass as a proxy to compare the areas of two sections that represent equal times. Next time, I might see if I can get my hands on some card stock or other heavier paper to make it a little more convincing that the small differences are negligible. I also will probably re-work my Kepler’s Law introduction to include Halley’s Comet right off the bat, rather than waiting until we introduce comets.

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Day 41: Central Force & Comet Orbits

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AP Physics: Central Force

Students used a Direct Measurement Video of a weight on a rotating table to find a relationship between force and tangential velocity. One of the first questions on my activity was to draw a free-body diagram of the weight and determine whether there is any net force. A lot of groups had some great discussion as they tried to rectify the fact that the table rotates with a pretty constant speed with the fact that their free-body diagrams showed a net force on the weight. There were also some groups that asked questions like how the speed of the banana compared to the speed of the weight, bringing them back to a Direct Measurement Video of a rotating disk we’d used earlier in the year.

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Earth Science: Comet Orbits

A major theme this week is comparing different kinds of solar system objects, so I decided to take an idea Michael Lerner gave me last week and have students compare the orbit of Halley’s Comet to Mars. I used an ellipse drawer to give students the orbit of both objects, then had them start by making some observations. Today, most groups only had time for the qualitative questions about the two orbits.

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Day 40: Mass & Craters

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AP Physics: Mass

Students worked on a lab practical to find the mass of an unknown object using a modified Atwood’s machine. My plan is to use spring scales to verify the mass the determined, then use this to introduce the difference between inertial mass and gravitational mass, but time got tight and most groups need a little longer to finish their calculations.

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Earth Science: Craters

During yesterday’s lab, it quickly became clear that my students did not have much sense of how craters are formed. Today, I got out some trays of sand and an assortment of marbles and we explored how mass and impact speed affect the crater size. I was really excited when the groups who finished early started asking new questions, like how the depth of the sand or angle of impact changes the crater, and coming up with experiments to answer those questions. This is why I love freshmen! We also dropped a shot put into a bigger tray of sand and got some slow-motion video just because its cool.

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Day 39: Assumptions & Moon Landscapes

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AP Physics: Assumptions
Some of my students are losing track of the tools they have for problems involving forces, so we started by whiteboarding as many different representations for a simple force problem as we could and then making a list of what we have in our forces toolkit. From there, students worked on some TIPERs problems. I had students answer each problem using a CER, but turned it into a CAER by asking them to state and justify key assumptions before diving into the evidence. We had some good conversation about what makes something an assumption rather than evidence or a claim. We will definitely need to revisit this as the year goes on, but I liked hearing my students start by articulating what they had to just agree is true before digging into the rest of the problem.

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Earth Science: Moon Landscapes

Students looked at a topographic map of an area of the Moon. They made some good observations and inferences about the craters formed, but students have had limited exposure to topographic maps so far and, as a result, had trouble connecting the map to what the would physically see. Next time, I think I’ll start by having them look at an actual image of the Moon, then transition to a topographic map of the same area.

Day 38: Pushing Blocks & Kepler’s 2nd Law

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AP Physics: Pushing Blocks

Students worked on a problem I’ve come to really like where three blocks of different masses are being pushed along by a certain force. Based on some of the struggles a few groups were having, I think it would be worthwhile to pause sometime soon to do a model summary. I loved the moment when students figured out how to use the 3rd Law to think about the normal forces between each pair of blocks. The best thing I overheard, though, was a student who said “You need to convince me you’re right! If you can explain your idea and your evidence, then I’ll believe you.”

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Earth Science: Kepler’s 2nd Law

Students plotted the position of Mars along its orbit, then cut out some wedges that represent the same amount of time. We used the mass as a stand-in for area to show that an orbiting object sweeps out the same area in the same amount of time. We got really nice results; the class average for the mass was within 0.01 g for the two wedges. I think students lost track of what they were plotting, however, so I need to think about how I can reinforce what the numbers they are plotting has to do with the actual path of Mars.

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