Most middle/junior high / senior high school students have P.E. classes. “P.E.” stands for “physical education.” There are various reason why school require their students to take a P.E. class – also called a “gym” (from gymnasium, the type of room the classes are held in) class. The Greeks had a saying: “A sound mind in a sound body” (mens sana in corpore sano, which is actually a Latin translation of the original Greek phrase!). They believed that physical fitness was an important part of mental fitness, and just as the mind needs to be trained, so does the body. P.E. classes are thus an important component of this training. They also provide students with the opportunity to burn off some excess energy, which in turn will help them to concentrate better when they return to the classroom.
Students in younger grades generally don’t have gym every day, but they do get the opportunity to run around and play at recess. When they do have gym class, the focus tends to be on organized activities that are easy for younger children to play and understand. Games like tag or kickball are common activities in these gym classes.
Older students usually have gym every day, partly because they have outgrown recess. They are more skilled and coordinated, so it is easier for them to play sports like basketball or volleyball. Sometimes a P.E. class might offer the chance to play individual sports such as tennis or swimming, but usually the emphasis is on team sports. They might also have tests in a P.E. class, but such exams usually test knowledge of game rules and the like.
Sometimes, if a high school student is on a varsity team, he might be exempted from P.E. classes for that quarter. That means that he would not have to go to gym class, and could use the time as a study hall instead, for example.