بسم الله الرحمن الرحيم
There are various types of children in a school; some children follow the habit of wicked children and adopt bad moral and become wicked like them. So should not worry much; rather both of you [parents] should pray for your child and keep on making him understand politely and with love.
Moreover, read Bismillahir Rahmanir Rahim (بسم الله الرحمن الرحيم) seven times and blow on food and drinks and all your family members should eat that food and drink that water. In-shaAllah it will have good effect on your child.
Allah knows Best!
Darul Uloom Deoband
This answer was collected from the official ifta website of Darul Uloom Deoband in India.