Lesson #347 of Teaching: Kids Respond to Incentives

Incentive: If you guys are well-behaved throughout the entire lesson, we'll go downstairs to the bake sale at the end of class, and I'll buy you each a cookie.

The Result: Impeccably behaved classes. Active participation. 90% engagement. (It's almost June, and I still can't get every kid.) And so almost all of my students now understand niches and the competitive exclusion principle.

And they love me, because I bought them cookies. Added bonus.