This question is controversial because it is different from a child to another one.
.... What is the question? ... you need to introduce the question to the reader in the introduction.
I can not completely agree with the statement that classmates are more influence than parents on a child s success in school.
... ok ....this is your position.
classmates have a significant effect on child s behavior and his or her success in school. Children spend much time at school. Classmates have many things in common such as age,interests, homework, and classes after all. So, they discuss their impressions about a new teacher, solve problems together, learn their homework, gain new knowledge and experience , and even make their own new discoveries. Sharing all these make them closer. Some of them become friends and they spend after-school time together. For instance , my brother was a good student at school he always got high grade, his classmate was not a good student. When he became my brothers friend, they spend most of their time together. My brother had a positive effect on him made him became a good student.
... this paragraph does not justify your position. In body paragraphs, you need to give reasons to strengthen your position and support them with examples.