school success of a child thanks to whom?
First of all, classmates can help us deal with our work at the school which hardly any parents can do. They can help us solve the maths or English, find out our mistakes in each exam, or something else. Parents have some generation gaps which made them can't catch up with our study. For example: if you have a big math problem that you can't solve, your parents can't help you because they forget or don't know how to deal with it, but your friends can do. They also can find out other ways to solve the problems more quickly and easily. We can learn so much from them.
Second, maybe sometimes parents have put us under pressure because of the mark at school. No matter how hard you try, your score seldom satisfies your parents easily. Classmates are known more about our school's mark. They know which exam is hard and which one is easy so they can sympathetic with us easier. And they encourage us to try hard for the next exam.
And the last, classmates are a motivation for us to try hard more and more to get good marks, they learn with us, point out our mistake to makes us better for the next time. They encourage us when we disappointed because of the bad mark. They help us a lot with our study in the school.
So, we sure that classmates have a big influent on the children's' success at school.