Give students a bunch of examples, then ask them to categorize. Then re-categorize. Then, yes, THREE-categorize.
Put these animals into groups. Then do it again. Then… do it one more time. How does re-re-grouping the same creatures reveal new patterns and give new insights?
Put these countries into groups. Then do it again. Then… do it one more time. How does re-re-grouping the same places reveal new patterns and give new insights?