# Fairy Tale Math Circle #2

Wait, what happened to the Fairy Tale Math Circle #1? And what is it in the first place? Well, some time ago I came across a wonderful Russian book called “Математические олимпиады в стране сказок” (издательство Белый Город). In it each chapter presents 8-10 math problems themed around one of the most well-known fairy tales. I immediately wanted to work through this book with the Rocket Boy (who recently learned to read Russian, woo-hoo!). And since math is a lot more fun when done with friends, the idea of a Fairy Tale math circle was born.

Meeting #1 was last Monday. The format was new to me (and I also decided to add a physics experiment at the end of each meeting). The weather wasn’t the best (we meet at a park). So it was pretty chaotic. No pictures and everything seemed a bit askew.

Starting this week I tried something different. I chose several problems for independent work and e-mailed them to the parents, one problem per day, in the days leading up to the meeting. Then at the math circle we concentrated on more interesting problems. I also signed up a volunteer photographer (thank you, Rocket Dad!). And I moved the meeting to a much nicer and quieter park (plus the weather was perfect).

As a result, today’s circle went so much smoother. I felt that the kids were more focused, more engaged and worked better together. Today’s fairy tale, The Magic Swan Geese (Гуси-лебеди) was about two little kids left at home by themselves. The older sister is supposed to watch her little brother at all times, but instead plays with friends. The magic evil swan geese snatch the little boy and whisk him away to the old witch in the forest. The sister marches off to find and save her brother, completes three challenges (all having to do with eating), and brings him back. End of story.

We started with a couple of algebra word problems like “If I had as many apples as I have now, plus that many apples again and four more apples, I would have 20 apples. How many apples do I have?” I expected these problems to be difficult for the kids who range between 6 and 9 year olds. And they were. Most solved them by picking different numbers and testing them. But we did work out a way to write down the problem using only math symbols (create an equation).

The next problem required coloring a geometric net of a cube so that when cut out and assembled, it looked just like the cube on the picture (shown from three different angles). D asked if he was allowed to assemble the cube first and color it later. Yes, of course! L and V went this route, cutting and assembling their cubes. Rocket Boy, for whom cutting is difficult, chose a different approach – analyzing the drawings and folding the cube in his head. Everyone struggled with this problem! But in the end, everyone solved it their own way.

My last problem for the day was a matchstick puzzle. I gave this very same puzzle to some of the same kids (Rocket Boy and L) at my math circle last spring. They found it very hard and couldn’t solve it. So today I brought it back. To my amazement everyone (!) solved this puzzle in less than a minute! Yay!

Then the math part was over and it was time for an experiment. In the fairy tale the big sister goes looking for her brother and comes across a river of milk. The banks of this river are made of something called кисель – a sweet drink made with fruit syrup or milk and potato starch. We’ve just mixed water and corn starch instead and ended up with a terrifically gooey oobleck. Of course, all of them saw oobleck before, but not everyone remembered their preschool days. Plus, it’s a fun project no matter how many times you’ve done it.

So we mixed it and mashed it and strained it. And talked about whether it is a liquid or a solid (the agreement was that it was both). What viscosity is. Does viscosity of water, milk or honey stay the same? What about oobleck? How oobleck’s viscosity changes?

I feel that the experimenting part still needs to be improved so we end up with a meaningful discussion and good questions. Will work on it for the next week’s circle.