The person reading your resume wants to read things that will show what kind of a person you are. What you are good at, what excites you. Write about the classes you got good grades in, school activities and clubs you participate in, any positions you have held in school such as class president or student council. If you have done volunteer work after school, be sure to include that as well. List any organizations you belong to (scouts, church choir, etc.). List hobbies such as model building and sports you participate in. If you have traveled outside the US, speak a second language or have made trips to famous places, list them as well.