Every trouble in a child's life is the result of something. Sometimes, simple unawareness in the childish psychology could cause many uncured psychological complexes and troubles. Every children psychologist suggests that it is better to prevent than to cure.
Peer pressure
Whatever the psychologists say about an importance of a child to spend more time in a peer groups, sometimes it is not the best leisure time for a kid. Peer pressure concerns the peer groups where children smoke, take drugs, lie or something like that. A child who is pressed to cut the lesson together with everybody is to be able to make his/her decision if it is worthy to do it. Self-confidence is an important helper to find strength to handle the desire to do "like everybody does". As a parent, you have to give some tips to a child who understand that some actions are wrong, but a peer group makes him/her doing something against own will. If your child has a trusted friend, it is easier to say "no" together and keep own line.
The children are doing that as they wish to stay respected, get along with the friends well, as it is very difficult to be an outsider at school.
The positive news is that peer pressure could be effective. For example, the children could share with their ideas for better studying; make sport together as it is considered to be fashionable. A child could be excited about some very interesting book and recommend it other kids. As a result, everybody starts reading it, and after that they are discussing the book.
Whatever it is, positive or negative, the kids need socializing to find the positive ways of development, discover own strength or find out the way to cope with the negative influence.