At this age, your kid would start getting interested in displaying his knowledge and skills. This is the age when his relationship with his friends takes an all new level. There might be kids trying to bully the others, ones that try being bossy and the ones that are possessive.
What you need to know
Your child might still be a kid in your eyes, but you might see him suddenly grow up in many ways. He might start competing with his peers at his school. He might start working hard to try and prove himself.
Your kid would love to please you as well his teachers. This might sometime make him try and compete with his friends. He might try to establish himself and try to show how he is better. He might become more sensitive. He would start expressing his opinions. He would also love to work independently.
So in a lot of ways he develops a unique personality at this age. This is when he learns how different he is from his peers and starts doing things that would make him contend with his peers. All you have to do is, encourage him to be himself. Teach him to compete in a healthy way and never to compare himself to others.