Play out some of the situations that your children are having trouble with, and show them how to respond calmly and firmly with words instead of actions. Children must understand that they have to wait for their turns, just like everyone else. Help your children understand the importance of sharing with others, in school and in life. Compliment them when you see them sharing with others. But also let them know that it's the kind of behavior you expect.
Children tend to behave badly when they are tired or hungry.
You can help your children by making sure they get enough sleep and nutritious food. When they admit doing something wrong, tell them that you would have been more angry or disappointed if they hadn't admitted their mistake. A family politeness policy. They'll soon catch on. Teach your children the importance of thanking people for gifts and other kindnesses.