Ask:
Fill old milk containers and soda bottles w/ water and freeze. Use them in your cooler instead of buying ice. Put them on top because hot air rises so the cold air will go to the bottom of the cooler. This also prevents food from getting soggy from melted ice.
Answer:
I bought some plastic reusable plates and cups that we take camping and on picnics, so we don't have to buy paper and disposables. It just takes a little water to clean them.