## Thursday, May 26, 2016

### 5/26 Magic Squares

My new numberphile t-shirt from the latest video arrived in the mail last week.

I decided this was a sign to do another magic square themed Math club properly dressed in the new shirt:

#### Preliminaries

P.O.T.W participation went up quite a bit this week. I'm pleased that everyone applied the Pythagorean theorem really well. In a related note, the kids were very excited to  report a Pythagorean error in one of their worksheets from class. This involved  a problem finding the volume of  a triangular prism where the values for the triangle face's side lengths were not consistent.  I'm glad to see this really stuck with them and that they tried it out in other contexts but it did necessitate a short "sometimes mistakes happen even in printed textbooks" speech.

I went with another battleship puzzle this week. I didn't check it as closely and the kids finished a bit quicker than I wanted. I'll either up the difficulty next time or more likely move onto to something  new.

#### Main Activities

For comparison last year went like this: http://mymathclub.blogspot.com/2015/04/428-magic-squares.html

While the warm ups were ongoing I struggled in vain with a video projector. In the end I had everyone crowd around my laptop to show the above video and the followup one since they're short.

Interestingly, some of the kids really latched onto the idea of finding a 3x3 magic square of perfect square and continued to talk about it all through the hour. Also I hadn't planned to do the following (assuming it wouldn't be interesting) but several kids also wanted to just find the the base 3x3 and 4x4 squares by themselves. So I  ended up telling them the sums (15, and 34) and that made them happy for a good period of time.

I then handed out the worksheets I had actually prepared:

Interesting this year, I learned something about internet material. There was a magic hexagon problem from the last year I wanted to reuse here but I had only stored the link. By this time it was no longer there and I ended not quite finding as good of a version as I remember. Its better to store a copy of your own of any material that looks worth reusing in the future.  This all sounds a bit slapdash in  recounting it but generally worked very well in the room. If I do this again, I think I'll  substitute in a magic square transformation type problem.

#### Problem of the Week

I'm going back with another MathCounts set:  https://www.mathcounts.org/resources/problem-of-the-week/taking-train