When the responding student sees the cup start to fall, she pulls her hand out of the way. The students take turns responding to the falling cup, recording results in order to determine the minimum distance from which an object can be released and still allow the responding student to avoid being hit. They then conduct the same kind of experiment with their non-dominant hand and foot. Finally, the students repeat a set of investigations after a period of practice on avoiding the cup. Afterwards, they evaluate the effect practice has on response time.
Food provides energy and materials for growth and repair of body parts.
Vitamins and minerals, present in small amounts in foods, are essential to keep everything working well. As people grow up, the amounts and kinds of food and exercise needed by the body may change. If germs are able to get inside one's body, they may keep it from working properly. For defense against germs, the human body has tears, saliva, skin, some blood cells, and stomach secretions. A healthy body can fight most germs that do get inside.