dy/dan

Nick Hershman is running laps with this one. Check the blog post or the screencast, in which he explains how he built a Python script around an algorithm from the comments.

Summer school right now involves six hours of Geometry instruction followed by three hours of planning for the next day's Geometry instruction, which basically leaves me fully tapped for tweeting, blogging, smiling, anything but sleeping. I'd say something laced with regret here but the fact is I enrolled some truly incredible students who challenge me and crack me up for the better part of those six hours. These kids make for light work.

Their proficiency does cause its own kind of trouble, though, because my strongest and weakest students space themselves out dramatically over six hours, requiring all kinds of differentiation. My favorite recent method, particularly with today's investigation of reflections, is to say, "okay, now do that with just a compass and straightedge."

I had a method in mind but several students each did me one better.

One student made kind of stunning use of SSS congruency. Another dripped sweat all over the page constructing perpendicular bisectors, copying angles, copying sides in an incredible (but functional) mess. Another used the method I chose but did it in three fewer arcs.

I have five more days to enjoy this.

[BTW: I have determined that at least 20% of this is garbage.]

Five uninterrupted hours of Geometry differentiated between credit recovery students and enrichment students turns out to be exactly as easy as everyone predicted it would be. After misjudging time-on-task about a dozen times and grossly overestimating our ability to construct an orthocenter by Just Playing With It, I did something at the end of class that I didn't hate.

I put up this slide and asked Mika to pick a point out. I asked her to tell Jason across the room which point she was thinking of. She stumbled and stammered a bit. "It's sort of to the left of the one that's near the center," etc.

And then I added labels.

And it became a little clearer why we label points. Mika relaxed. Everything looked easier.

In 2007, I told my students that we name lines using two letters and I gave several examples. Today, I asked Mike how he would tell Kelsie across the room which of these lines he was looking at. First, it was easy.

Then it was difficult.

The same went for how we name angles.

This math thing is easier to approach if I ask myself, what about this concept is useful, interesting, essential, or satisfying, and then work backward along that vector, rather than working toward it from a disjoint set of scattered skills. There is probably a book I should read somewhere in all of this.

Postscript

Also: I didn't hate our opening exercise in which I gave each student a) a compass, b) a straightedge, and c) a map of the Meyer family's South Pacific archipelago, Meyeronia, and d) five questions. [pdf]

1. How many miles is it from Kenneth to Christy?
2. Which island is farther from David? Barbara or Christy?
3. List all the islands that are three miles from Kenneth.
4. Find a location in the water that is the same distance from Tom & Bob. How many are there?
5. Find a location in the water that is the same distance from Tom & Bob & Kirsten. How many are there?

I like this. The iPhone application RulerPhone will measure anything, in any photo, so long as the photo includes a credit card. It's a great use of proportional reasoning, which, if pressed to name one, would be The Mathematical Skill I'd Most Like My Students To Retain After High School.

I added it to the What Can You Do With This? segment featuring The Bone Collector, which seemed like an obvious pair to me. In trying to find the best classroom entry point for this program, I can only think of the question, "How can we break this thing — trick it into giving an incorrect measurement?" I imagine someone can do better.

Session Title

Games And Puzzles That Develop Sequential Reasoning

Better Title

OMG MICHAEL SERRA!!1!

Presenter

MICHAEL SERRA!!1!

Narrative

A structure not dissimilar to Megan Taylor's yesterday, where Serra debuted games and puzzles and gave us time to tease them out.

I sat with two former colleagues in the back — all of us now at different schools. One teacher enthused over Sudoku puzzles. They challenge kids. Kids like them. It gets them comfortable with numbers. The other enjoys Serra's games and puzzles, like Lunar Lockout. Both cite improved student disposition toward math and improved deductive reasoning.

I disagreed with them. In general, I find it dangerous to put too much distance between "fun time" and "math time" preferring, instead, to have that cake and eat it too, creating as many challenges as I can that are both fun and mathematically rigorous. (Which Sudoko, to put it plainly, isn't.) My task is harder, I think, and I know I fail at it more, but I'm more satisfied on balance.

It was a good conversation. Feel free to interrupt us.

Serra's best offering for my money was Racetrack Math:

It's like this:

1. Draw a racetrack on graph paper, however crude.
2. You and your opponent start anywhere on the starting line.
3. You travel along vectors. You may increase or decrease either the x-value, the y-value, or both, but only by one unit per turn.
4. First person to the finish line wins.
5. (P.S. No crashing.)

This gets very interesting very quickly. You start out with tiny vectors which lengthen by one unit every turn. If you fail to notice the side of the track off in the distance, though, and fail to slow down in time, you crash. (Which I did in the example above.)

I hereby toss all of my battleship exercises in the recycling bin. This is a much more straightforward introduction to positive/negative coordinates since each new turn is relative to the last turn rather than relative to this strange coordinate axis thing.

Plus, your students can create racetracks of their own, of infinite complexity, within seconds. Serra cited some kids who created a pit lane, which you had to enter on your second lap, and oil slicks, on which you could not adjust your vector at all. I'm impressed.

Visuals

PowerPoint. Which is tough when you're asking people to solve a puzzle. If someone suggests an alternative route to the one you have programmed into your slide, you have to dodge their answer a bit.

Handouts

Blank puzzles and games to draw on. Again, paper is not dead. How do you do this digitally? Load each picture one at a time into Skitch and pass a stylus back and forth? Moderation, please.

Homeless

• "There is no research that demonstrates these games improve outcomes in other mathematical procedures like two-column proofs," Serra admitted reluctantly. "It has to be there. I know it is.