A tool for exposing what a computer is actually doing.
I teach, among other courses, “Introduction to Programming”. Because of the strange power of the private corporation known as “The College Board,” I teach it using Java.
Verbosity is useful when teaching. It exposes things that a student could otherwise miss. But there is a lot of Java (and every other language) that is not exposed: in particular, computers are so very fast that the temporal aspect is almost completely invisible. It is slightly more visible with an imperative language like Java than with something like OCaml, Haskel, or Forth; but it is still mostly hidden.
Feel free to hammer away at it and make suggestions in the comments below. I’m not yet convinced the visualization I have is the right one.