Quick Idea from #TMC13August 4, 2013
I just thought of this as I was reading some recaps of TMC13: During “My Favorites”, Chris Lusto offered the idea of having students work out the definition of a circle.
What just struck me was one of the activities challenged the students to come up with an example that fit a classmate’s definition but was not a circle. COUNTEREXAMPLE!! Counterexamples (especially geometric counterexamples) are so tricky for students to get. Here’s a built-in example of why they’re a big deal. Love!