130 A conceptual student analyzed a video of Super Mario jumping. I think she mis-estimated Mario’s height, which is what she used for a scale in LoggerPro, but apparently Super Mario’s world does have fairly reasonable gravity. Cool!


Video Physics

129 Conceptual students are doing a video analysis project, and this is the first one to try using Vernier’s Video Physics on her iPhone. She is pretty pleased that she figured it out! And so am I!


104 These are a few of our videos for analysis in the conceptual classes. The last clip in the video is in “instant replay” mode. Students will be producing several graphs and answering questions designed to help them connect projectile motion to the balanced force model and the unbalanced force model.



Off-topic kid

97 Today kids were in a variety of states of progress on the acceleration video analysis. One student who had finished earlier than others was playing this game, Bubble Trouble. (My posting about this will probably result in the game being blocked at school. Playing games on school computers is against the district Acceptable Use Policy.) I took a few videos (and I will probably take some more at home) so when we do projectiles we can do a video analysis to check if the game’s physics matches up with reality physics. So while the student was off-topic, this game may turn out to be useful!





96 The data are starting to come in from the video analysis. Not enough yet to tell what the graph will look like. I decided to pull all the data together in a Google Doc.


Fan Cart

94 The conceptual classes are going to determine how much force a fan exerts on a fan cart by comparing acceleration to mass. I have never tried this before so it will be interesting to see how it works out. Each group has a video with a different amount of total mass. They will get acceleration from video analysis and then we will make a whole-class graph. Maybe all three conceptual classes will contribute data to one graph with lots of data! Ooh!




66 Today some conceptual students did their first “practicum.” They timed how long it took the slow-acceleration disk to roll one meter down its ramp. Then they had to determine how fast it had been going when it passed the 1-m mark. While they timed it, I took video. While they debated how to find the answer, I did video analysis. They told me the answer was 0.16 m/s and then Tracker told me the answer was 0.164 m/s. So I told them that they got it right. They were a little stunned, I think, and I hope they were also proud of themselves for doing it. Next step: more complicated questions.


Preliminary Graphs


58┬áSo, the data from the videos is not bad! Not everyone has actually managed to collect the data yet, however, as some students have technical difficulties. I’m always amazed when students can’t figure out how to find a file or save a file. I expect by the end of the year my students will have it figured out! I have found that it is important to have all the kids doing individual work for things like this, or only one kid from each group will learn how. One year I had students join my class mid-year who had somehow managed to always get others in their groups to do their work. My kids straightened them right out in terms of using the computers!


Speeding Up

57 We are starting constant acceleration particle model (CAPM) in the conceptual classes, and this is the first time I’m doing CAPM with students who know the difference between balanced forces and unbalanced forces. Another first is doing the paradigm lab using video analysis, so we started with each group making a video to analyze with a different number of bricks creating the slope. I use the apparatus I learned to make from Rex Rice when I took the Modeling Instruction workshop in 1997. It’s a disk made of particle board with a couple of golf tees for an axle. It rolls surprisingly slowly down a ramp made of two pieces of conduit, held at constant separation by two pieces of 1×2 with equidistant holes drilled in it. In the past I’ve had students mark the conduit with dry-erase markers and use stopwatches for timing. I’m hoping for better data this year, as well as teaching the students to use video analysis.


Two for the price of one

I could not decide which class I wanted to talk about, so you get two photos today. The top one is from one of my conceptual classes, a great example of a mistake in which students assume that there must be some sort of straight upward force to balance the gravity force. This is the way all the FBD’s we made at first were laid out. In this problem, there should not be any surface force at all, which the system schema clearly shows. So we discussed that in class. I also spent time talking about how important this mistake was for everyone’s learning and in a later class I asked a group to add this particular mistake to their FBD, which they found distasteful but they did it anyway.

The second photo represents the successful use of Tracker to analyze a rotational motion video. I have a collection of 8 videos which I made several years ago and students have always done the analysis in Logger Pro, clicking through hundreds of frames. Ugh! Happily, last summer I learned how to use Tracker and all the groups were able to have Tracker autotrack a spot on the cardboard “record,” a process which wound up being painful in much different ways. I could go on and on about the technical issues we had but happily most of my students are resourceful and some are handy with tech support, so every group now has data to analyze. We’ll be doing that tomorrow.