First, kids don’t always like to talk about this to parents or teachers.

Second, boys are more violent than girls and their need to express themselves in rough and tumble play is not considered enough at school and society.

With that said, here is a good article about talking to sixth graders about moving up to secondary school:

https://www.socialandhealth.com/short-courses-in-the-community/lets-talk-going-secondary-school-workshop-6th-class-pupils/