I don't know how old you are, but if your an "older teen" you could tutor. Depending on your references (get them from teachers, coaches, ect.), grades, age, maturity, subjects, etc, you could stand to make some serious dough. I charge $30-40 an hour depending on the students needs.Your guidence department might be able to take your number to give to any interested parties.
Edit: Wait, did your topic mean to say how can a ten year old earn money? If so, sorry. I read it as how can a teen earn money. Ignore the idea if you are only ten.