Trace back to their continents of origin all the food you ate today. Try to explain how they came to be considered breakfast, lunch, or dinner food.
Trace back to their actual location of production your foods for today. Figure out how much energy, how many people, trucks, planes, etc were required to serve you breakfast, lunch or dinner.
Check out just how much food we throw away after each meal. Figure out its caloric value and estimate how many people it might have fed.