[__t__]

I agree factorial is very clearly defined with self-references but I think that the answers have no clear meaning and that's why its not an optimal way of teaching recursion. Teaching examples that have meaningful answers IMO allow for much better reasoning

[ledauphin]

agreed - it's the intuitiveness of the answer to the example that is so critical to building understanding. When you want to teach a method, it's much better if the student already knows what the result should be by a different method, so they can see how the new method is different than the one they know.