Experiment

[Pip]

A science teacher decided to conduct an experiment to show his students the benefits of a healthy lifestyle. He took four jam jars. In jar one he put cigarette smoke. In jar two, alcohol. In jar three junk food and in jar four good clean dirt. He then put an earthworm into each jar, sealed them and put them in a cupboard.  At the end of a week he took the jars out and showed them to the students, saying. "Look, the worm in the cigarette smoke is dead, the worm in the alcohol is dead, and the worm in the junk food is dead. However, the worm in the dirt is alive and well. What do we learn from this?"

One young student put up his hand and said, "If we smoke, drink alcohol and eat junk food, we won't get worms."