One more thing about this!

I forgot to mention how much I love the design of Stan's puzzle. Stan credits this interlocking puzzle design to George.
I've been playing with it constantly over the last couple of days when I can, investigating the different solutions for different numbers of semicircles to find patterns. I love it because the design is so simple and easy to manipulate and when I come up with a solution, I just take a picture of it. To me, this is very powerful. Because its hard (for me anyway) to investigate a problem like this without a manipulative. So this is great for me to play with and try to figure out the patterns behind it. Once I get this, then I can delve into the math already understood about it and see if my discoveries match up! What fun! Puzzles and math is so amazing!