Please don't teach trees as undirected graphs

I think I&rsquo;m not alone in suggesting that the tree, and perhaps the binary tree specifically, is the most foundational data structure in computer science. This raises the question of how binary trees should be introduced, and I&rsquo;d like to make the case that introducing binary trees as a special case of undirected graphs is not a good idea. I can see reasons why you might think this is a…