# Days 68-72: Energy & Forces

This was another week that was a little messy. I had a sub Wednesday through Friday so I could present some of my doctoral research at the ASTE conference. On top of that, we had an ice storm early Wednesday morning that resulted in a late start, so two of my classes didn’t meet

AP Physics 1: Energy

This week was all about applying our model of energy transfer. We had some great discussions before I left where students were navigating how different systems affect the problem. We also did some TIPERs problems where some common preconceptions came out. The last few years, I’ve been working on being more intentional about making sure we discuss what’s correct about those preconceptions and whether there are other questions those ideas are the correct answer to. My students this year have been really receptive to those conversations, which makes for fun discussions and seems to help kids feel comfortable sharing ideas. Once I left, students worked on an energy lab practical in Pivot Interactives and some energy problems from the College Board’s AP Physics 1 workbook. My students were a little nervous about doing those problems without a teacher who knows the content in the room, but I’m betting they will make some good progress with peer conversations.

Physics: Unbalanced Forces

Students started working problems using unbalanced forces. My students and I are getting more comfortable with each other, which is leading to the discussions getting better. That’s helped me make the connection that the reason some of my students have been struggling with the direction of some forces is they don’t have a great conceptual understanding of the interactions involved in some forces, especially the normal force. I made sure we spent some time reinforcing those ideas by doing some things like using the matter model for normal force and a pair of hairbrushes for friction. My go-to move is to place those on a board at different angles to help students get a visual and tactile hook to make sense of what direction the normal and friction forces should go, which seemed to help a lot of students. We also spent some time looking at how the normal force an elevator passenger experiences connects to the acceleration of the elevator. Once I left, they did an unbalanced forces lab practical in Pivot Interactives.

# Days 64-67: Kinetic Energy & Newton’s 2nd Law

This week was a little goofy. Tuesday was our first day back from break, then a big winter storm meant we had to close schools on Wednesday. We used up our regular snowdays in December, so Wednesday was an emergency e-learning day, which means students completed asynchronous assignments.

AP Physics 1: Kinetic Energy

Our first task back from break was to find the relationship between velocity and kinetic energy. I waffle every year whether to do this with tracks and probeware, which as the advantage of being firmly rooted in the real world for students, or use Pivot Interactives, which has the advantage of measurements that are easier to make. With the weather forecast, I opted for Pivot. I had students complete the first section that takes them through making measurements and modeling the energy transfers with energy bar charts individually, then complete the remaining sections in groups. It’s been a little while since we linearized a graph or developed a mathematical model from data, but I was really pleased with how they did.

Physics: Newton’s 2nd Law

Our big goal this week as a paradigm lab for Newton’s 2nd Law. In some conversations last year, Kelly O’Shea suggested using carts on ramps as an alternative to the more standard modified Atwoods machine. Students used a force sensor to measure how much force it took to hold the cart in place. Next, we used some vector addition diagrams to reason out the force they’d measured is the same as the net force when the cart is released. Students used the motion encoder carts to determine the acceleration, then changed the angle of the ramp and repeated their measurements. I really like that this is conceptually much simpler than the modified Atwood, so students can focus on making sense of the data, and this approach makes a really clear conceptual link between balanced forces and unbalanced forces. For the e-learning day, we had students do some reasoning with vector addition diagrams of balanced forces to help review those skills to support the lab.

# Day 36-40: Newton’s Laws & Whiteboarding

AP Physics 1: Newton’s 2nd Law

Students used a modified half-atwoods to find a relationship between force and acceleration. The quality of the results varied a lot. I’ve been talking to the AP Chemistry teacher, and we think part of what’s going on is students aren’t often asked to use their data in meaningful ways before they get to physics, so it doesn’t make sense to take the time and attention to collect data carefully. I need to put some thought into how to help students place value on good data collection and build the skills required to collect good data.

After developing Newton’s 2nd Law, we spent some time combining the new equation with vector addition diagrams. Students are starting to buy in to the diagrams as useful thinking tools, which is always a lot of fun to see.

Physics: Free-Body Diagrams

Students have been working on Newton’s 1st Law and drawing free-body diagrams. We have some problems that often lead to great discussion with mistakes whiteboarding, but I’ve been struggling to get students in one of my hours to speak up during whole-class discussions. To help with that, I tried doing a short gallery walk prior to any of the whiteboard presentations this week. Once the whiteboards were ready, I had students visit each board with their group and make notes on their worksheet about potential mistakes they saw or questions they had. During the whole-class discussion, there was a lot less silence and we heard from some students who don’t often speak up, which was exactly what I was hoping for. I think it also helped that I shared those goals with students before we started. When a student joked those goals aren’t going to happen, I assured her I’m very stubborn and am convinced the class can get there.

# Day 59: Board Meeting, Impulse, & Particle Diagrams

AP Physics 1: Board Meeting

We had a board meeting for yesterday’s lab on Newton’s 2nd Law. Overall, students got very nice results and were very successful at making sense of what they saw.

Physics

This group added some notation to their graph to find the units on their slope

Physics: Impulse

Students used an elastic string to tie a cart to a force sensor in order to find a relationship between the cart’s change in velocity and the area of the force vs. time graph. I’ve tried this lab a few times without great results, so spent a lot more time on the pre-lab than I had in the past and its looking like results will come out fairly nice.

Chemistry Essentials: Particle Diagrams

Students looked at the change in mass as they spread out a piece of steel wool and started drawing particle diagrams. My co-teacher and I agreed we want to ramp up the graph interpretation in the course, so we made a histogram of the class results and spent a fair amount of time discussing them. Students had some great observations about the graph.

# Day 58: N2L, Momentum Intro, & Mystery Tubes

AP Physics 1: Newton’s 2nd Law

Students worked on collecting data for a relationship between force and acceleration. It was a lot of fun to see students able to just dive right in to a lab like this; it was a good reminder of the growth students have made so far this year.

Physics: Momentum Intro

Students worked on a lab my colleague came up to introduce momentum. Students caught a cart at the bottom of the ramp, then came up with as many ways as they could to make it tougher to catch the cart, similar to the chalk smashing analogy used in the Physics Union Mathematics curriculum to introduce energy.

Chemistry Essentials: Mystery Tubes

This trimester, I’m re-teaching the first half of the course to a brand-new group of students. We started today by getting out the mystery tubes. There was a lot of great conversation, both in small groups and in the whole-class, which was a lot of fun, especially since we really struggled to get that in the class last trimester. I’m really excited for this group of students.

# Day 44: Whiteboarding, 2nd Law, & Whiteboarding

AP Physics 1: Whiteboarding

Students whiteboarded some constant acceleration problems for a gallery walk. These problems are coming very easily to most of my students, which is great to see.

Physics: Second Law Lab

Students collected data for a paradigm lab on Newton’s 2nd Law. Some students were a little thrown off by recording values from a graph in a data table, then making a new graph from the data table, but that’s fairly common.

Chemistry Essentials: Bohr Model Whiteboarding

We whiteboarded and discussed some key information from the periodic table and Bohr model for several different elements. Students lit up at the end when I had them leave off the name and the number of protons, then have another group try to figure out which element they’d answered the rest of the questions for.

# Day 71: Board Meeting, Practical, & Density Again

AP Physics: Board Meeting

Students whiteboarded their graphs from yesterday’s video. Once I had my 2nd hour find a class average for the slopes of their vertical velocity vs. time graphs, everything fell beautifully into place and there were even gasps when one student sketched a free-body diagram. In my other hour, a lot of groups skipped the directions for making the v-t graph and tried to take shortcuts that didn’t work, so I had to step in a little more. This reinforces my thoughts yesterday that I should have spent some time discussing the midpoint method.

Physics: Unbalanced Forces Practical

Students started a practical to predict the time it will take a cart to roll down a ramp given the cart’s mass and the ramp angle. For the first time, I had several students ask if I could just do a diagram or calculation for them, so I left the pen I usually carry at my desk and kept my hands in my pockets to avoid encouraging that.

Chemistry Essentials: Density Misconceptions

Today, I have students blocks of the same material, but different volume, and asked them to determine whether volume affects density. A lot of groups had trouble funding the volume with a ruler, rather than later displacement, so I should have spent a little more time on a pre-lab discussion connecting yesterday’s volume measurements to today’s.

# Day 68: Whiteboarding, Problem Practice, & Whiteboarding

AP Physics: Energy Predictions

Students whiteboarded drafts of their answer to which interaction dissipates a bouncy ball’s energy. One of the things I like about this activity is every group agreed the table is where most of the energy is dissipated, but there was a variety of evidence cited that gave some good opportunities for discussion. Afterward, I showed a thermal video of a weighted tennis ball and we played with the happy/sad balls and seismic accelerator.

Physics: More Problem Practice

Students got some additional practice with unbalanced forces in 2D. It was one more day than I think was truly necessary for their understanding, but confidence has been a big struggle this year and it seemed to help a lot of them feel like they can do the problems.

Chemistry Essentials: Mistakes Game

I did the mistakes game with yesterday’s problems, and it was very rocky. I think it wasn’t ideal timing to introduce whiteboarding since tomorrow is our last day before break and a lot of students are very restless. I’m also really struggling in Chemistry Essentials, more than when I’ve taught it in past years, to get students focused on chemistry during chemistry.

# Day 67: Video Analysis, Speed Dating, & Density

AP Physics: Video Analysis

Students continued working to determine whether a bouncy ball dissipates most of its energy from impact or from air resistance (I’ll have an article about this activity in the January issue of The Science Teacher). Today, students used LoggerPro to analyze the videos they made yesterday and collect evidence. There were a lot of great conversations about connections between energy and motion, which is exactly what I’m after with this activity. Most students had a draft of a CER about where the energy was dissipated by the time they left class.

Physics: Speed Dating

As part of my effort to focus on lowering the social stakes in my class, I had students do some whiteboard speed dating to go over yesterday’s goal-less problems. There were a lot of great conversations; the best part was how many students I heard asking “How do you know?”. My 1st hour in particular did a great job of finding and correcting mistakes in each others’ work. I also am continuing to talk about my pedagogical choices more than usual, which seems to be helping students go along with what I’m asking and hold each other accountable for participating. Particularly in my 1st

The units got fixed on the next rotation, but I forgot to snap a new photo

Chemistry Essentials: Density

We discussed the results of yesterday’s lab to get to a definition of density. I skipped doing a true board meeting because, with break looming, I was worried about time, but students didn’t have as solid a mental model of density as I would have liked when they were working on the worksheet. It was a good reminder that pedagogical shortcuts have their cost.

# Day 66: Missing Energy, Goal-Less Problems, & Mass vs. Volume

AP Physics: Missing Energy

Students started working on an activity to determine whether a bouncy ball mostly dissipates energy due to air resistance or due to the impact with a table (I’ll have an article on this activity in the January issue of The Science Teacher). Today, students worked on sketching LOL diagrams and velocity vs. time graphs for each explanation, which lead to some good conversations about the connections between energy and motion. Each group also recorded a video of a bouncy ball that they’ll analyze in LoggerPro tomorrow.

Physics: Goal-Less Problems

Students worked on some goal-less problems for Newton’s 2nd Law in two dimensions. I was very explicit with my students that I use them to make it okay to start a problem without knowing where you are going. We also spent some time discussing key steps students should take (like deciding whether the forces are balanced or unbalanced, drawing and annotating diagrams, etc) which helped a lot of students see where to start.

Chemistry Essentials: Mass vs. Volume

Students worked on finding a relationship between the volume of water and its mass. I had students design their own procedure for the lab and I think they could have used more pre-lab discussion; I usually keep the pre-lab pretty short in favor of doing a lot of coaching lab groups, but the class is bigger than usual this year and I was spread pretty thin, which in turn fed some classroom management issues. I’ll need to keep that in mind for future labs.