Author: Marta R. Stoeckel

Day 125: Board Meetings & Molar Mass

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AP Physics: Lever Board Meeting

We had the board meeting to discuss the results of the lever lab. A few groups were quick to notice the slope slope on the force graph was the ratio of the distances to the pivot, while the slope on the distance graph was the ratio of the masses they used, which lead nicely into a definition of torque.

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Physics: Pendulum Board Meeting

In my first hour, the board meeting was pretty rough with a lot of very long silences. I forgot this was the first board meeting of the trimester and about half of my students had the other physics teacher last tri, so I should have taken more time to set up the board meeting. My other hour is a little more talkative to begin with, but I also spent more time prepping for them discussion and things went much better.

Chemistry Essentials: Molar Mass

Students applied molar mass to some real-world problems, such as finding how many moles of chalk it took to write their name. Students are approaching the calculations for number of moles very algorithmically without much sense of why they divide the numbers they do. I need to think about how to make the why more apparent; I’ve discussed some analogies, such as bank tellers counting pennies by weight, but I wonder if it would be helpful to actually carry an analogy out in the lab.

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Day 124: Levers, Pendulums, & Molar Mass

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AP Physics: Levers

Most students did not finish their data collection on the Universal Gravitation lab, so I decided to postpone the discussion. A lot of students prioritized data collection on Monday, then ran into trouble doing calculations in a spreadsheet and weren’t comfortable asking for help electronically since they don’t have much experience with that. It was great to see, however, how many students were enthusiastic about trying their hand at spreadsheets.

In place of the discussion, we jumped ahead to levers to introduce torque. Students first placed the clamps at set positions and found a relationship between the mass hanging from one side and the force required to balance the lever. Next, students picked two masses to use and found a relationship between the distances from each mass to the pivot required to balance the lever. One student commented the second part of the lab reminded her of using a triple beam balance.

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Physics: Pendulums

Students predicted the period of a pendulum at the main entrance using their data from Monday. A lot of groups used a linear fit and predicted a larger period as a result. We didn’t get to the board meeting today, so tomorrow we’ll have a chance to get into why that happened.

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Chemistry Essentials: Molar Mass

Students practiced finding molar mass and the number of moles in a sample. When students get stuck, particle diagrams have been a huge help since they force students to break down what the formula actually represents.

Day 123: Universal Gravitation, Pendulums, & State Testing

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Today, sophomores and juniors are taking state tests, so freshmen and seniors have an off-campus learning day. This is the first time we’ve done something like this and the guidelines were pretty flexible. Both of my physics courses are mostly seniors.

AP Physics: Universal Gravitation

Students finished graphing their data from yesterday’s lab using exoplanet data. I started a thread on Google Classroom for students to post questions to try and encourage some virtual discussion, though it didn’t get any action as students opted to e-mail me, instead. Most of the questions I got related to uncertainty, which is not surprising. There were some great conversations yesterday about uncertainty, including why some measurements had different values for the plus and minus.

Physics: Pendulums

Students worked on graphing and linearizing their data from yesterday’s pendulum lab. I usually give students time in class to linearize their graphs so they talk to me or their group members, but they’ve had enough experience at this point that it shouldn’t be a huge leap to do it independently. A few groups didn’t collect all their data yesterday, so I posted a link to PhET’s pendulum lab so they could still be on track for tomorrow’s board meeting.

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Chemistry Essentials: State Testing

My chemistry students are juniors, so they took the ACT today to meet state testing requirements and were off the hook for the off-campus learning day.

Day 122: Universal Gravitation, Pendulums, & Formula Mass

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Today was our first day back from spring break! We have kind of an odd start to the week since tomorrow freshmen and seniors have an off-campus learning day to accommodate state testing for sophomores and juniors.

AP Physics: Universal Gravitation

Students worked on an activity Lucas Walker presented at AAPT last summer using exoplanet data to find a relationship between centripetal acceleration and orbital radius. I was nervous about having students calculate the orbital velocity and acceleration in a spreadsheet since most of my students don’t have much experience with spreadsheets, but my students were very willing to dive in using the resources I provided and were very successful with the calculations.

Physics: Pendulums

Students collected data to model the impact of weight, drop angle, and mass on the period of a pendulum. I’m continuing to see students much more confident in their physics abilities than even the end of last trimester, and working more independently as a result.

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Using the environment to make measuring release angle easier

Chemistry Essentials: Formula Mass

Students started making sense of formula mass by predicting the mass of various combinations of nuts, bolts, and washers. I wanted to give them something pretty concrete they could test directly in the lab before diving into true stoichiometry. When we shifted to chemical formulas at the end of the hour, a few students got tripped up if they skipped the particle diagram, but the math was pretty obvious to everyone once they got that step.

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Day 121: Free Response, Practical, & Quiz

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Today is the last day before spring break.

AP Physics: Free Response

We took some time to look at the free response problems from the tri 2 final exam. A lot of students ran out of time on the final, so we spent some time discussing strategies for time management and steps they can take even when they think they are lost on a problem. We didn’t talk about anything ground-breaking and even the physics seemed pretty clear once we got into it; I think the stress of finals got to students and made it tough to use skills they know.

Physics: Projectile Practical

Students wrapped up the horizontal projectile practical from yesterday. One of the advantages of doing projectiles after energy is I didn’t trip up any groups by switching out the marble for a lighter one. Usually, I get at least some groups that do some wild math to try and figure out what the mass changes, but this year’s students either pointed out the mass never showed up in their calculations or used conservation of energy to show it doesn’t matter.

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Chemistry Essentials: Quiz

Students took a quiz on balancing and representing chemical reactions. I always have a few students in this course who have trouble staying quiet once they are finished; today, all of the conversations I shut down while students were testing were about problems on the quiz, which was pretty awesome. I felt a little bad telling them it wasn’t the right time for those conversations, especially with how passionate the conversations were.

Day 120: Practicals & Demos

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AP Physics: Central Force Practical

I got out the record player and, as a class, we found where a mass starts to slip when the player is at 33 1/3 rpm. Students then calculated what radius they should place the same mass at when the record player is at 45 rpm. Since the velocity depends on the radius, the math got a little hairy, but students were pretty successful working through it and making sense of how all the variables were connected.

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Physics: Projectile Practical

Students rolled a marble down a short ramp to turn it into a horizontal and predicted where it should hit the floor. Both my classes were able to complete it with less support than I expected. After each group managed to hit the target (an old carbon-copy referral form), I asked them to predict where, relative to their first marble, a lighter one should land.

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Chemistry Essentials: Demos

Students balanced a few different chemical reactions, then I demonstrated those reactions. Most of the students seem to be getting pretty confident with both skills and enjoyed the demonstrations. The thing I struggled with is the demos felt very separate from the balancing since they did confirm or otherwise add to the work students had done. I’m wondering if there is something I could have done differently to connect those two pieces better.

Day 119: Whiteboarding

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AP Physics: Central Force Whiteboarding

Students whiteboarded some problems dealing with a central net force. My students who have taken Astronomy are pretty excited with the connections they are seeing to orbits. I also pulled up a simulation of Newton’s Cannon to talk about a problem that asks why the ISS doesn’t crash into the earth.

Physics: Projectile Motion Mistakes

We did the mistakes game, focusing on the diagrams and initial set-up for problems rather than all of the math. There are a lot of long silences, so I might try giving students some structure for additional pre-discussion with their lab groups next time. Maybe students could do a gallery walk and jot down some potential questions for each whiteboard. There are a lot of groups opting to use “vertical” energy to solve for key values, which is pretty cool.

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Chemistry Essentials: Balancing Mistakes Game

We did the mistakes game with yesterday’s problems on balancing chemical equations. I’ve got the opposite problem of my physics class, where lots of students have things to say, which leads to too many people talking at once. Most of my contributions end up being to re-focus the discussion or redirect students, rather content-related questions to move things along. I’m okay with this problem, even if I’m not sure how to solve it yet.

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Day 118: Board Meeting, Projectile Problems, & Balancing

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AP Physics: Board Meeting

We had our board meeting for yesterday’s lab on centripetal force. I approached it as three mini board meetings since students had done experiments for how three different variables affect the force. The units on slope ended up being a very powerful way for students to see the connections between their three graphs. It was especially exciting when we got to the force vs. mass graph and students saw the connections to Newton’s 2nd Law. One class noticed the slope on the force vs. 1/radius graph has units of Joules, but I’m not sure of the significance of that yet.

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Physics: Projectiles

Students whiteboarded yesterday’s problems for a gallery walk. They are consistently viewing free-fall as just a special case of models we’ve already covered, which made the problems pretty easy.  Afterward, students started working problems for horizontal projectiles.

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Chemistry Essentials: Balancing Reactions

After some discussion about the labs from the past few days, students worked on some problems balancing chemical equations. The students who started by sketching a particle diagram were generally very successful at seeing how to balance. A few students got tripped up determining when individual letters in a formula represent individual atoms, especially when the formula included a polyatomic ion, but were getting the hang of it after a couple problems.

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Day 117: Central Net Force, Free Fall, & Balancing Equations

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AP Physics: Central Net Force

Students worked on an activity in Pivot Interactives to find how speed, mass, and radius affect the centripetal force. One of the great things about this time of year is my students not only have a lot of skills, they are very confident in those skills, so I got to listen to good conversations about experimental design, uncertainty, and linearization without stepping in to do any coaching.

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Physics: Free Fall

Students worked on some free-fall problems. There was a pretty even split between groups who relied on velocity vs. time graphs and groups who relied on energy. For the first time, I had a couple of groups draw separate v-t graphs for when the object was rising and when it was falling, which helped them organize their thinking.

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Chemistry Essentials: Balancing Equations

Students used the PhET Balancing Chemical Equations sim to start exploring what it means for a chemical equation to be balanced. This not only seemed to help students make sense of balancing, but to do some retroactive meaning-making on the work we’ve been doing on representing reactions.

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Day 116: Multiple Choice, Reaction Time, & Conservation of Mass

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AP Physics: Multiple Choice

Students took a quiz on rotational kinematics and we fired up Plickers to discuss some multiple choice problems a lot of students got wrong on the final. There were a lot of great conversations and students generally felt very comfortable pointing out errors in their own thinking. There were a few problems that most students got right on their first try today, which was interesting. I asked my students about it, and they said they were feeling pretty mentally fried during their final, especially since it was on the second day of exams, which makes sense.

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Physics: Reaction Time

Students dropped rulers to calculate their reaction times. Students were pretty successful at designing an experiment and sketching a velocity vs. time graph for the ruler, but annotating and setting up equations was much more challenging than I’d hoped.  Doing the math with v-t graphs just isn’t sticking for a lot of students this year. I think the problem is a lot of them are not attaching meaning to the variables or numbers, which makes the annotations on the graphs and the formulas we use something to memorize. I need to keep working on supporting my students in using the graphs and other diagrams as tools for meaning-making.

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Chemistry Essentials: Conservation of Mass

Students did a chemical reaction in a plastic bag to see the conservation of mass and practice translating between different representations of chemical reactions. Time got a little tight because I was not able to have a balance at every table; next time, I would be better off delaying the lab if another class needs the balances on the same day. Students still got a kick out of the chemical reaction.

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