## Tuesday, January 12, 2016

### 1/12 Human Calculators

This week Math Club started up again although sadly without my son who had a fever and stayed home.  There are seven new kids to get to know and I'm on a good start memorizing their names. Hopefully after another week or so I'll have them down. We started this session by going around and having every kid introduce themselves, their class and if they were new why they joined and if they were returning what their favorite activity from last session was. There was a lot of "My parents signed me up" from the new kids which hopefully isn't a sign of true motivation. Based on the work afterwards I'm not too worried.  It was also interesting to see what problems struck a chord:

• The toothpick / matchstick problems from Martin Gardiner were mentioned several times.
• The logic grid puzzle came up. I knew everyone likes those from last year.
• Interestingly one kid mentioned the practice math relay.
I then did the club charter talk. As I mentioned last week the 3 key points I like to emphasize are:

• Basic behavior expectations. As I told the kids "You guys were great last session so hopefully I won't have to mention these again."
• The importance of listening to others when they are demonstrating their work and not just listening but actively thinking/evaluating their strategies.
• What to do when you're stuck. I had the kids especially those from the first session volunteer ideas for this part of the talk.
From there I jumped into the icebreaker which I chose because it gets everyone moving. I decided to call it A.L.U. after the arithmetic logic unit chip but I didn't tell the kids straight off the meaning of the acronym.
The rules are pretty simple. Everyone lines up initially sitting . I had 3 groups of 5.  The goal is to get the last person in the line to stand up. Each turn the team uses the following rules.

1. Anyone may sit down.
2. The person in the front of the line may sit up or sit down.
3. Everyone else may only stand up if everyone in front of them is standing up but if they do so the people in front must then sit down.

This ends up being pretty exciting for the room. After the first iteration I had the kids break into two groups instead and told them to think about what we were doing and how it related to arithmetic.
After letting them brainstorm for a few minutes I hit gold. One boy volunteered: "Does this have something to do with the binary system?" I wrote down some of the beginning iterations using 1 for standing up and  0 for sitting down,

1
10
11
100

And from their we had discussion about a binary counting. I wish I had more of these type activities in my back pocket (with movement) They are always appealing. Perhaps, for another time, I may have the kids design adders using logic gates.

For the back half of the session, I did end up using  Matt Enlow's congruent shape worksheet:

This was highly popular and kept the room humming.

My only regret was not having enough time for a linked tangram/tetris activity.  Finally I gave out a problem of the week based on an AoPS video I happened to watch recently:

Bobo the wonder clown is walking across a train bridge when he hears a train whistle behind him. He’s 45% of the way across the bridge. Whichever way he walks he’ll get off the bridge just as the train arrives. If the train is going 60 mph, how fast is Bobo walking?

I like this problem because of the conceptualization necessary to solve it. We'll see next week how high the participation rate is. Overall this week had great flow. I came away feeling exhilarated.