Bezier curves are actually my favorite way to teach recursion. They give a nice visual representation of what's happening, the base case is pretty straight forw

Bezier curves are actually my favorite way to teach recursion. They give a nice visual representation of what's happening, the base case is pretty straight forward, and so is the math. The time-step element adds just enough extra complexity to take it beyond "let's sum a list" or "check if a string is a palindrome".