This week was the first of a new school year. I’m trying to shift my approach this year to make inquiry a central feature of my classroom, pulling ideas from a few different sources, including Modeling Instruction and the 5E model. Whenever someone tries to change things, some aspects will be great and some will have room for improvement.
In the past, the other physics teachers and I have introduced constant speed by measuring the time at set positions for a bowling ball rolled down the hallway. The lab works fairly well, but the logistical issues (including the number of people and the space needed to collect the data) mean that the lab is done as an entire class. I wanted to have each group collect their own data and played with various options using equipment we have. I settled on using ticker tape and dynamics carts. Since this would be their first exposure to ticker tapes, I knew students would need instruction over how to use them. I started with a discussion (borrowing some ideas from Kelly O’Shea) to determine we’d need to measure position and time, then showed students how to use the ticker tape to measure each of those. I wanted students to make some experimental design decisions, so all I added is that students should have a table of their cart’s position and time by the end of the period.
It did not work. I underestimated how much mental effort using the ticker tape would require from my students, so they had a lot of trouble dealing with the other decisions I asked them to make. I also wasn’t explicit that students should make a written note of what they were trying to produce, so a lot of students forgot what they were supposed to do by the time they managed to get a tape with a nice series of marks. During my first hour, I ended up pausing the lab a couple times to give some extra direction when I saw multiple groups struggling with the same issues. In later hours, I provided a lot more structure right from the start, including prompts for students to write down information they would need to reference later. Fortunately, my first hour students were pretty forgiving; I think it helped that I’ve talked to them a bit about the shifts I’m trying to make and why, so they saw where I was coming from.
I was pleased with how the analysis of the lab went, however. I’d hoped to have students try creating a few different types of graphs using Plotly to get at why a scatterplot is the best option for a position vs. time graph, but I wasn’t able to get my hands on a netbook cart, so stuck with a short discussion. My students were able to agree pretty quickly that a scatterplot was the best option and were able to articulate why. Each group then graphed their data and performed a linear regression using either Desmos or the TI graphing calculators most of them have. Groups sketched their graphs on whiteboards, and we had a class discussion looking for similarities and differences in the graphs. Thanks in part to how many students have already taken AP calculus, students were able to pretty easily identify and articulate what on the graphs had physical meaning, which meant I didn’t have to deliver any lecture on constant speed.
Moving forward, I’ll save tools unfamiliar to my students, such as the ticker tape, for labs where the data collection is pretty structured, rather than try and use them for open-ended labs introducing a new topic. This year, that may mean some compromises, such as collecting data as a class or other large group and keeping items (like motorized constant speed buggies) in mind for this spring’s order.
I also want to keep working on how to have effective class discussions. I had several students tell me how much they loved that I lectured less than 10 minutes in the first week and I have every intention of keeping that number as low as I can. In order for students to continue to get the content out of discussions, I need to improve my skills at facilitating them. That will mean lots of reading, lots of formative assessment (to see if my students know their stuff), and lots of reflecting on how discussions went.
All in all, I’m excited about the shifts I’m making. I’ve loved seeing more of my students’ thinking on display this week and they’ve been very engaged so far. There will definitely be more hiccups and missteps, but those are just opportunities to learn.