My husband and I raised 3 boys. We went through a "mountain" of cheerios in that time: they ate them for breakfast and snack, fed some to the dogs, stuffed some in couch cushions, crushed several million on the floor and into the rug, and of course they were used for various crafts, not to mention projectiles!
The other day, the chimney man came to replace the liner in the chimney. The new liner came in this amazing box. I begged them not to throw it away. Cheerios came to mind and the following video was the result.
Cheerios in a chimney box
I am still working on what the problem will look like. I think I may just show it to my Geometry students and hold a competition for the question or questions that we need to answer. I kept the lid to the box in case they want to do something along the line of Dan Meyer's penny question (http://www.101qs.com/1193-penny-circle).
Feel free to make suggestions! I am VERY new at this! :)