One of my classes was catching onto proportions fairly quickly and I wanted to give them an activity where they could apply those skills.
I found this link to a lesson called Hands on the Giant. I projected a giant hand onto paper and traced one for each group. Their instructions were to find the height of the giant just knowing how big its hand was. I gave them no hints and let them work.
Immediately some groups were measuring themselves and their hands and then setting up an equivalent proportion. It was great to see them pull from the math they knew to solve this problem.