Mass & Weight

Day 33: Problems, Board Meeting, & Assessment

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AP Physics 1: Problems

Students worked on some conservation of momentum problems, including Michael Lerner‘s watermelon on wheels, that require them to be flexible about the system they are using. A lot of groups went straight for a whiteboard once the work time started, which lead to some great discussion and collaboration on the problems.

Physics: Board Meeting

We had a board meeting for yesterday’s force of gravity lab. This was actually the first traditional formula students got from a lab this year. During the discussion, I could tell my students are getting much better at making “for every” statements about the slope and describing the meaning of the intercept.

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Chemistry Essentials: Assessment

Students took their quiz on phase changes. One problem talked about a generic chemical, rather than something specific, which threw several students off. It was a good reminder to keep problems firmly rooted in real situations. Afterward, we revisited the mystery tubes from the first day of class as preparation to start talking about the periodic table and atomic models.

mystery tube

Day 32: Board Meetings, Gravity, Invented Problems

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AP Physics: Board Meetings

Students whiteboarded their results for the collisions lab and the center of mass video analysis from last week. Between the two labs, I think students started to see why it might be useful to switch between systems when thinking about momentum.

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Physics: Force of Gravity

Students worked on a lab finding the relationship between mass and the force of gravity. Whiteboards are ready and looking good for a board meeting tomorrow!

gravity lab

Chemistry Essentials: Invented Problems

To review phase changes, I had students write their own problems and exchange whiteboards with another group. There were a few groups that had some good conversation as they were writing their problems and there was some good cross-group conversation when comparing answers after working another group’s problem.

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Day 23: Board Meeting, Annotating Graphs, & Gas Laws

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Today was students’ last day before a 3-day weekend and our homecoming pepfest, so classes were short and students were more energetic than usual.

AP Physics: Board Meeting

We had a board meeting for the spring force lab. Students initiated some good discussion about the intercepts in both sections, but I had to do a little coaxing to get them thinking about the values of the slopes. One of the challenges was a lot of groups hadn’t distinguished between mass and force of gravity, which tells me I should have done a little more pre-lab discussion, especially since that distinction was just introduced earlier this week.

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Physics: Annotating Graphs

Students whiteboarded yesterday’s problems for a short gallery walk before trying some calculations. I think this is the first year where I didn’t have any students opt to use the formula for the area of a trapezoid on any of their graphs; it just felt more natural to most of my students to split the graph into a triangle and rectangle (which is what I usually do). When students started working with numbers, I had a lot of students independently start talking about specific times and velocities as coordinate pairs, which I haven’t seen students do before and was pretty great.

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Chemistry Essentials: Gas Laws

Students sketched their graphs from the past few days for a simplified board meeting. One of the things I really appreciate about this group is I have some students who are really willing to speak up when they are confused about something; one of my students was struggling to see how the graphs fit with the qualitative relationships we found earlier this week and didn’t hesitate to say so, which lead to some valuable discussion about how to read a graph.

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Day 21: Board Meeting, Quiz, & Quantitative Gas Laws

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AP Physics 1: Board Meeting

Students finished up their whiteboards for yesterday’s lab and we had our board meeting. Both classes got really nice results and had good discussions. I’m thinking about moving balanced forces to right after constant velocity next year since it gives some really good opportunities for students to be successful on experimental design.

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Physics: Quiz

Today was our quiz on representations for constant acceleration. The quiz was pretty short, but I’ve been giving a few minutes before each quiz for students to do a reflection on their collaboration over the past few days. I also spent a few minutes talking with my students about today’s Nobel Prize announcement, and my students had a lot of questions about both this year’s prize and the Nobel Prize in general.

Chemistry Essentials: Quantitative Gas Laws

I am being compensated by Pivot Interactives for participating in a pilot of their chemistry materials.

Students used Pivot Interactives to collect data for a relationship between pressure and temperature. There were some minor issues with the computers, but once students got logged in they were pretty successful. We only have one gas pressure sensor in the school, so this particular activity makes it possible to do a quantitative lab we otherwise wouldn’t be able to and is more firmly rooted in reality than a simulation. The activity included some questions I really like the temperature when the pressure is zero; I overestimated how well my students understand the intercept of a graph, so I’ll need to make sure I allow time to discuss those questions tomorrow.

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Day 20: Force of Gravity, Graph Stacks, & Gas Laws

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AP Physics 1: Force of Gravity

Students collected data to find a relationship between the force of gravity on an object and its mass. Not surprisingly, data is coming out pretty nicely. This is also giving students a chance to have some good conversations about uncertainty since their cognitive load on the rest of the lab is a little lighter.

gravity lab

Physics: Graph Stacks

Students whiteboarded some problems from the Modeling Instruction curriculum sketching kinematic graph stacks for a cart on a ramp, a few of which we tested using a ramp with a motion encoder cart. I also got out Brian Frank’s magnetic vectors for the first time, which made it much easier to discuss the motion maps. For the problems we couldn’t test, I had students whiteboard a problem, then get with a group that did the same problem to come to a consensus, which lead to some great conversations between groups that disagreed.

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Chemistry Essentials: Gas Laws

I got out some sealed syringes to do a qualitative exploration of ideal gas laws. Students made some great observations, and developed a nice, kinesthetic understanding of what pressure is.

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Day 83: Inertial vs. Gravitational Mass, Board Meeting, & Freezing Lauric Acid

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Several nearby districts had snow days today, so most of my classes were a little more off-task than usual today.

AP Physics: Inertial vs. Gravitational Mass

Students finished collecting data and making graphs for the period of a spring lab. We didn’t have enough time for a board meeting, but every group had decided mass is what matters so we took a few minutes to decide whether it is gravitational or inertial mass by comparing the period of a cart on a spring at different angles. This is the first year I’ve used the Pasco equal length springs, and several groups were able to get some pretty nice data for period and spring constant.

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Physics: Board Meeting

Students whiteboarded their results from last week’s lab. I gave different groups different springs, and the slopes reflected that variation nicely which lead smoothly into fitting k into the formula. I had conversations with some groups about whether their results were “right” that reinforced just how uncomfortable some of my students still are with being even partially wrong. Talking to them, I think they don’t see this fear of being wrong as an obstacle to learning physics.

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Chemistry Essentials: Freezing Lauric Acid

We worked on a lab to find the freezing point of lauric acid by melting it in a hot water bath, then making a temperature vs. time graph as it cools in a cool water bath. This is the last class of the day and we ended up getting released 13 minutes early due to a snowstorm, so only one group was able to get data. Especially since a third of the class was gone by 6th hour, I’m thinking about just repeating the lab tomorrow.

Day 11: Uncertainty, Buggies, & Norms

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AP Physics: Uncertainty

We had a board meeting on yesterday’s force of gravity lab, and the discussion was better than I expected at this point in the year. As we were talking about the slope, one student claimed “Gravity doesn’t change”, which lead nicely into what we mean by that and how we know. In response, another student shared that yesterday one of her group members said “The force goes up 10 N for every 1 kg of mass”; after finally reading Arons this summer, one of my goals is to have students make “for every” statements about slope, and I was thrilled it came up naturally.

I also introduced uncertainty during the board meeting. Students had a lot of great observations about the relative precision of measurements and how much mass it took to change the reading on the scale, which gave them a sound conceptual basis. I rushed the discussion since the end of the hour was coming, and it ended up more teacher-directed than I’d like, but I’m pleased with how the basic approach worked.

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Physics: Buggies

Students collected data for the buggy lab. Since when I ask for observations, there is usually a student who says the buggy is moving at a constant speed, I took a page from Michael Lerner and framed the lab as seeing how we can find out. A few groups are starting to make “for every” statements about their slope, which I did not see during the introductory unit and is great to see. I think the relationship is more obvious here than it was in the intro labs.

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Chemistry Essentials: Norms

I’ve been struggling with classroom management. This is a very high-energy group, and there are a lot of things that are a lot of fun, but I’ve been having trouble keeping them on task and getting them to voices besides their own. I decided to pause today to spend some time developing norms as a class. I think a lot of students felt it was punitive, but many also agree that things aren’t working at the moment.

Day 10: Force of Gravity, Lab Practical, & Volume

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AP Physics: Force of Gravity

Students collected data to plot the force of gravity on an object vs. its mass. I had different groups use spring scales with two different ranges. Tomorrow, I’ll use the different levels of precision to motivate a discussion of uncertainty. Groups with the 50 N spring scale have already noticed that the smallest hanging masses don’t noticeably change the scale’s reading, which is exactly the kind of observation I was hoping for.

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Physics: Lab Practical

Students revisited the dowel lab, this time as a group assessment. Their results on the original lab weren’t as good as I was hoping, but they are looking much better now that students have had an opportunity to discuss the flaws in their original approach.

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Chemistry Essentials: Volume

Students found the volume of several different shapes, then measured how much water was needed to fill each one. Some groups got beautiful results, but other groups struggled. I think the groups that struggled had trouble matching up their measurements to the formulas on the cheat sheet I gave them or the Google calculators I showed them. A lot of students also also had trouble measuring the amount of water they put into the shape. The groups that struggled with these measurements were also the groups that were the least focused, but I’m not quite sure which issue is the chicken and which is the egg.

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Day 140: Types of Mass & Seismometers

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AP Physics: Types of Mass
I wanted to revisit gravitational and inertial mass, so I got out the inertial balance and asked which type of mass a spring’s vibration should depend on. Finally, we used the motion detector to find the period with and without a string supporting the added mass and got beautiful results.

Afterward, students worked on some free-response problems in their groups. Tomorrow, they will get limited time with the scoring guides, then present their assigned problem.

Earth Science: Seismometers
Students built a very basic seismometer, then experimented with recording different types of earthquake waves. The results varied a lot, but it did lead to some good discussion on the limitations of the earliest seismometers.


Day 100: Rotational Energy & Weight

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AP Physics: Rotational Energy

Students whiteboarded yesterday’s problems and we spent some time discussing how changing the system changes the LOL diagram. I picked a problem where a block on a spring becomes an upward projectile and a second where a block is launched by a spring up a track; I really liked using this pair since it drives home that path is irrelevant in conservation of energy.

Afterward, I had students use conservation of energy to predict the velocity of a marble at the bottom of a ramp, then we measured with photogates. Their prediction was off by about 60%, which I used as motivation to introduce rotational kinetic energy to account for the “missing” energy at the bottom. When students saw the actual velocity, they were quick to attribute the difference to friction, even after seeing the percent difference, so now I’m wondering if there are other good ways to rule out friction. Maybe time the marble down the track, then compare the acceleration to the component of gravity along the track?

marble

Physical Science: Weight vs. Mass

Students weighed hanging masses on spring scales to find a relationship between weight and mass. We moved this to the start of the unit since its the one thing we do with forces that doesn’t fit with our engineering project, but I feel like weight ended up separated from other important ideas from forces. As we dig more deeply into forces this week, I’ll make sure I circle back to the concepts of weight and mass, so I may decide this sequence was okay after all.

weight