While spending half day waiting at the Bangkok hospital, I manage to inflict my sister with an introduction to recursive functions. What's really cool, is that she totally got it and loved it. Here are the exercises we did:
1) Write the logic to calculate the Factorial of N.
2) Write the logic to calculate the Factorial of N, without using a loop.
3) Write the logic to calculate the Nth number in the Fibonacci Sequence.
(Next family vacation: data structures)