You should probably watch this video, too:
In truth, if you would like more practice with higher-order functions, and you would like to use this laboratory as part of your portfolio, then I would encourage you to include the Higher-Order Functions Contest work as part of your portfolio submission. It is a duplication of problems from the previous lab, but you are asked to rewrite them using map and fold. Most of them are one-liners, but may take a touch of thought.