**Friday, 24 January 2014**

I was off today to attend a workshop at the adoption agency that my wife and I have just signed up with. My students completed a classwork assignment independently.

**Friday, 24 January 2014**

I was off today to attend a workshop at the adoption agency that my wife and I have just signed up with. My students completed a classwork assignment independently.

**Thursday, 23 January 2014**

The last classes in my rotation finished their bumper buggy lab today. All of them predicted a collision location and time then tested to see how far off they were.

About 80% of my kids used something I characterized as guess and check for predicting the buggy crash: They figured the position of each buggy after 1 second, then 2 seconds, then 3 seconds. Once the kids realized the crash (for most groups) was somewhere between 2 and 3 seconds, they started figuring buggy positions for half second increments. Most groups did a little “eh, this looks about right” interpolation here. Some kept breaking the time intervals down into smaller increments to be precise. Though a few of these groups did say “there’s got to be an easier way”, none of them seemed really interested in testing it.

About 18% wanted to use a graphical solution — recognizing that the buggy crash happens when two linear functions intersect. They needed support transforming the linear functions they plotted using video analysis the day before into the new start location and direction I dictated today. For instance, kids whose buggies traveled in the negative direction didn’t come up with “duh! I need to multiply my original slope by -1” on their own.

Only one group suggested an algebraic solution to find where two functions intersected. But dang, was I proud of that group. They, like the group above with graphical solutions, needed some help formulating the equations of the two lines.

Why do these labs take me so long? The constant velocity buggies lab took 2 days with all of my classes. Due to our rotating schedule, I don’t see kids every day, so it looks like the lab stretched all week.

Here is the highlight reel of collisions:

Note to self: Next year, I’m modifying the Bumper Buggy game to use longer distances between buggies and create situations with radically different buggy speeds. It’s no fun to predict a crash within 2cm of the center of a 2m long course.

Generally speaking, I love the system I’ve worked out for partial credit. Kids take a test on Moodle, hit submit, and get immediate results as well as the correct answer to every problem.

If their answer is wrong but they can correct it before turning in the test work, I offer partial credit. Kids must classify their error as math or physics, point out where they went wrong, and show correct work.

This kid doesn’t get it. Or maybe the kid is kidding him/herself. The”weird math mistake” is a farce. Later, the kid claimed “calculator problem” on the same type of mistake.

Most of my students understand the partial credit business and genuinely reflect here. I have a few (under 15%) who refuse to be honest with themselves. Solution: next test, if you’re wrong about the mistake classification, I’m not giving you partial credit.

**Tuesday, 21 January 2014**

On Day 1, students used video analysis to determine their buggy’s speed. Today, I assigned two lab groups to play Bumper Buggy against each other. Both teams got a starting point and were asked to predict a collision location (and time). I didn’t tell them how to do it.

The group in the following video used a graphical method (shout out to Desmos — it was the kids’ introduction to the world’s best graphing tool).

Another student used algebra to predict a window of times between which the collision would occur (as in, her prediction sounded something like “the collision will happen between 1.7 and 2 seconds and between 1.1 and 1.3 meters from the blue buggy”).

“How would you know if your buggy moves at a constant velocity? What would you need to measure? How could you make those measurements?”

I introduced video analysis as one convenient tool to use. In one 70 minute period, kids filmed a buggy run, imported videos into Logger Pro, and learned the basics of video analysis.

Resources: the lab as a Word document, my raw footage, and a video analysis tutorial video.

**Wednesday, 15 January 2014**

I love me some mechanics but my students hate the topic. I can’t say there’s a lot of love in the classroom today for kinematics, forces, energy, and momentum. Maybe it’s because they spent a full semester of physical science on mechanics.

We start off with the ball bounce lab so popular with the modelers — not only do I hope to build some enthusiasm but I also want them to see the quantified direction we’re going in. Not all my labs can be described so succinctly but I see “can write lab instructions on the whiteboard” as a design goal. I think that 10-page lab handouts are where I lose most of my kids (in attention AND understanding).