We spent this week on the a=F/m paradigm lab. Once the students got their data whiteboarded, I began to see some problems — serious problems. The close relationships I had seen during my practice runs were nowhere to be seen: instead, the students had graphs dominated by systematic errors and an assortment of unorthodox, confusing ways to represent their data.
The picture above looks alright, except that the reciprocal of the slope (about 0.4 kg) is rather different from the 0.2 kg one would expect. Other groups clearly had trouble getting consistent data.
And others clearly haven’t bought in to the idea of the course.
In the evening, I replicated their experiments, and got results akin to the first graph. Today, I re-did the experiment with my hover disc, with only moderate improvement. It seems that the modified Atwood machine really needs a dynamics track to work. Drats. Maybe next year I will try to build an air track with a shop vac.
After two weeks of picking up skills — proportional reasoning, LoggerPro — we spent today’s class in board meeting (with a couple recesses to work up things) assembling the Constant Acceleration Particle Model. Unfortunately, for a variety of reasons, we didn’t get really convincing values for 0.5a, a, and 2a on the x/t, v/t, and v/x graphs. We used video of a plastic orange being dropped from a height of 3 m. I had hoped for a digression about terminal velocity (the last 3 frames, generally) but there was too much else to chat about.
Afterward, we started worksheet 1, from the modeling materials. It is, in many ways, a re-hash of the same process. I think this is valuable because I think some of the meaning was obscured with new technology (LoggerPro) this time around. By the end of class, most students were about halfway done. Since the task wasn’t new ideas, the students didn’t need much support, and it wouldn’t take more than 30 minutes of honest work to finish, I assigned the rest of the worksheet for homework. We switched to Managebac this year and, judging by students reactions, it seems to do a great job of listing their tasks and homework.
I am looking forward to deploying the model next week as we solve problems. Highlights will include misconception hunting, trying
king forward to deploying the model next week as we solve problems. Highlights will include misconception hunting, trying out goalless problems
out goalless problems, and getting the students to take more risks and initiative in board meetings.
Today we wrapped up our Constant Velocity Particle Model. The test is tomorrow. We went through one of the Modelling worksheets, which I thought was quite good, and I had the students work on whiteboards to prepare a summary of the model.
After the whiteboards were finished, I had the students do a “poster session” in which one partner stays by the board while the other visits others, and they switch after a few minutes. I think it was a good way to give students some time to wrangle with ideas and get their thoughts together. I circulated as well, and planted ideas for the eventual, short, board meeting.
The first board in this post was voted by the students as the clearest. The second board, I thought, also did a good job of summarizing the main information. My favourite hashtag appears in the bottom left corner. Disappointingly, neither board has an equation to describe the line, even though we developped those last week. I will try to reinforce the point for the next model.
Whiteboards are fantastic. I have been using them in so many ways over the past week. Today, I found a stash of tiny whiteboards. They’re fantastic! I’m going to try to put together a post with practical information and research results about whiteboards.
I should now link to some resources: