Im just wondering, why isnt it an elective?

Answer 1

Most educators consider physical education a vital part of everyone's education. It not only teaches rules of games, but more importantly, hopes to instill lifetime habits of exercise.

Answer 2

P.E. is a time to achieve physical activity. To obtain a healthy living style you should exercise for 60 min a day. Most kids/teenagers would probably not chose to do that therefore schools decided to include that needed exercise in the kids' school time.