Well, you can guess the punch line: this was more structured, but it, too, had so many things to look for that
it was too unwieldy to be usable. Happily, though, we had reached the point where we were focusing on the right
stuff. That is, all the things we were sure were important were there to be looked at; the problem was that they
were arrayed in a giant mosaic in which the key dimensions, whatever they were, were buried. So I did a classically
mathematical thing, which was to sort them into equivalence classes. For each item, I asked, “What is this an
instance of?” And, suppose we cluster together all the things that are of the same type. Can we identify that cluster
as an important dimension of a lesson?