Mountain Climber, an activity I posted about earlier this week, is seriously a gold mine for me. Yesterday, my kids were disappointed when I told them we'd already spent two days on it and we wouldn't be working on it for a third day in a row. Their faces looked like I'd cancelled Christmas. Who am I to tell kids they can't do challenging math problems? "On Thursday," I promised, "we can finish. We just need to do something slightly different today." So, the kids got back with their groups and labored their way through the final tiers of Linear Programming Mountain Climber. Rarely discouraged, they worked tirelessly to get correct answers. Some of them worked on problems over and over to find and correct mistakes. That mountain kept them working. I didn't have groups give up; they kept going and going until we ran out of time.
Moral of the story: sketch a crude mountain, find some playing pieces, and come up with a series of problems that increase in difficulty. Watch in amazement.