## Wednesday, April 6, 2016

### 4/5 Snap Cube Hotel

Before this week's Math Club meeting I had an extra math adventure. This weekend was the Julia Robinson Festival at the UW (http://jrmf.org/). I drove to the campus intending to wait on the side while about half of my kids participated. But the organizers ended up needing volunteers and so I manned tables for about 2 and half hours.  This was a ton of fun and I received a free volunteer T-Shirt. I was able to work one on one with about a dozen kids over the time. My favorite part was an interesting observation at the first table which was centered on chess pieces. If you attach the top and bottom of a square to each other and then the left and right you get a toroid! This is very easy to verify with a piece of paper folding it one set of sides at a time but also something I had never considered. Next year I intend to volunteer to help ahead of time.

Back on topic, while brainstorming for activities for the last session I came across the following interesting activity from @fawnpnguyen:  http://fawnnguyen.com/hotel-snap/.  I couldn't procur snap cubes quickly enough to use it last week but one of the third grade teachers got back to me and I arranged to borrow her supplies this week.

The basics are you break the group up into teams who design a "hotel" built out of snap cubes. These groups then earn income given one set of rules and are charged costs based on another (see rule sheets). I thought this would probably take the whole session but I printed an extra sheet of problems from the Julia Robinson Festival just in case. http://jrmf.org/problems/LittleBoxes.pdf  It turns out the process took the entire hour as expected (and everyone had a really good time playing around with building designs). I reserved the last 10 minutes for scoring and if I repeat I'd bump that up to 15-20 minutes.  The range in designs was really interesting and we didn't even probe all the optimization issues possible.

For the problem of the week I chose the current uwaterloo set which involves a number triangle from http://cemc.uwaterloo.ca/resources/potw/2015-16/POTWB-15-NN-24-P.pdf  This is not too difficult and hopefully will lead to lots of students trying it out.

Looking forward my backup idea would make a great session on its own. I will definitely try out a mini Julia Robinson problem set in future weeks.