At 5 and 6 years of age, a child is typically developing a sense of self. And, this new sense of self-identity enables a child to feel like they are part of a group. When he feels accepted, he accepts others.
Blossoming Communication Skills
To be able to cooperate, a child needs to communicate by listening to others, as well as, speaking honestly about his own needs and feelings. When a child feels valued, he values others.
A Growing Need to Gratify
Making friends and pleasing adults helps a child behave in ways to compete for attention, typically by wanting to be helpful. When his contributions are accepted as worthwhile, he contributes and cooperates more.
A Feeling for Fairness
This age expects that everyone should be treated equally, even if they can’t agree on what that is. And, they cooperate best with rules they helped to create.
An interesting by-product of self-acceptance is increased overall happiness.