Seems over-complicated, e.g. I probably wouldn't go for recursion for Fibbonacci, so I'd miss your expectations completely. Why not just ask a direct question on things that you're looking for? If you care about recursion, ask them to implement simple recursive tree walker or something. Equally linked lists are something that in modern languages almost no one will have to manage by hand. If you care about understanding the concept of pointers/refs, why just not asking directly about that.