20121129-154724.jpg55¬†Well, not everyone gets it yet. But, this class overall did better than the next class, which had less time to think about their mistakes and generally doesn’t discuss things at all. Purple writing is student commentary, red writing is my commentary.




54 I am trying something new. With one class, we explicitly discussed preparing for assessment. We’ll see if that discussion motivated anyone to study in the ways we discussed and if it helped anyone when we have today’s (day 55’s) assessment. (I fell asleep before posting this last night. That is why I am posting it today, for yesterday.)


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.



I made a completely new version of Kelly’s “Practice 2” from the Balanced Force Particle Model. And by “completely new” I mean that I reprinted another copy for everyone, giving more space to each of the situations on the sheet. My students were unable to include the system schema, FBD, and force vector addition diagram in the space on the first version, and I felt that the system schema was pretty important. The conceptual-level ¬†kids have a hard time doing the FBD without the system schema. So I made it a two-sheet, four-sided document and we are working through it focusing on balanced vs. unbalanced, directions of forces, and force vector addition. So far, so good. Assessment on Thursday!



50 Today students are using our ancient laptops to upload and edit video. Since for some reason Windows Movie Maker isn’t allowed to download the codec for .AVI files (huh?) we are uploading to YouTube and editing there using the “remix” function. It is a learning process. A few students are filming extra scenes, and a few more are trying their luck with the library’s computers to see if they are any faster. I like this project and it seems to have cemented some understandings about Newton’s first and second laws of motion for a number of kids, but video editing can be a long slow process.


Cup Bowling

49 Some students had some extra time after working on their bowling ball video in class, so they decided to bowl against plastic cups. Fun Friday!


48 Today the AP class was doing the ballistic pendulum lab. They found the launch velocity both by the projectile range method and the change in height of the center of mass of the catcher apparatus containing the ball bearing. This is a traditional piece of equipment. Some students used more modern equipment, as seen below:



47 I stayed home sick for two days. That head cold really hit me hard. But I am better now and the conceptual classes are making videos with bowling balls! Some groups are more dramatic than others. The videos are due Tuesday the 20th, and if any groups agree to share the links I will post them. We’re also continuing to discuss forces and equilibrium.



44 Sometimes it is easier to go to school than to write lesson plans for a sub and explain to a couple of different teachers how to proctor an AP makeup test. Especially after getting in after 10 PM and already feeling sick. But even with a steady intake of decongestant and expectorant, I felt miserable today with a head cold. So instead of actively teaching, I showed part of part 1 of The Elegant Universe. I wanted the conceptual-level kids to see the “electromagnetism is stronger than gravity” bit and the four fundamental forces of the universe in particular, since we are still in the Balanced Forces unit. We’ll talk about this stuff more later.