In the basic CS/Math classes at my school, trees are usually covered early in the course, usually along with proofs by induction. I think this might be a usefu

In the basic CS/Math classes at my school, trees are usually covered early in the course, usually along with proofs by induction. I think this might be a useful approach to carry over to your site. Once someone understands trees well, I think it allows them to understand graphs better when they learn that a tree is a just a type of graph.