donutI was the substitute teacher for a second-grade math class that was learning about groups. In one exercise, pupils were asked to label a group of items according to their common characteristics.

Pictured were onion rings, doughnuts, a bundt cake, and ring cookies. The correct answer would have been that all the items have holes in the center.

But one health-conscious boy's response was, "All of those things contain too much cholesterol."