Use the fact that a balanced diet is ultra-important to astronauts to help focus students' attention on the importance of a balanced diet in their own lives. Contrary to popular belief, astronauts no longer eat dried ice cream, chicken in a tube and other weird space food. Single-serving containers keep foods fresh and make them easy to eat. Several dishes are affixed to a tray that the astronaut attaches to his or her leg. Astronaut silverware is like ours, only it includes scissors for opening packages.
Some foods stay fresh in space without additional processing.
Other foods must be treated to prevent microbes from colonizing them. Some foods are dehydrated for astronauts to rehydrate in orbit. These foods include macaroni and cheese, soups and scrambled eggs. Sometimes, removing some of the moisture is enough to keep microbes at bay. Beefsteak is the only food that's irradiated for sterilization.