Begin by teaching the basics of manners, such as saying "please" and "thank you," as well as customary table manners. Create a game where children pantomime bad table manners and you show them the proper behavior, for instance chewing with mouths closed. Make a list of sayings, words and actions related to both good and bad manners.
Enlist the help of a volunteer to show that it is important to wait your turn. Point out to children that they should say "excuse me" when they want to be heard, rather than speak over somebody. Use role acting with the help of a volunteer to emulate the appropriate behavior, which is to politely wait one's turn while listening to the person speaking. Include the class. Allow them a chance to take the place of the volunteer while you continue reinforcing the appropriate behavior. Incorporate the aforementioned list so children can memorize it.
Generate a role playing exercise in which children learn that name-calling hurts. Demonstrate the importance of good sportsmanship. Explain through conversations with children why they should respect differences. Point out how fascinating it is that people around the world are so diverse. Show a video of how different cultures do things differently.
Have children practice what they learned daily. For example, have them hold the door for each other and reward them when they say "please" and "thank you." Help children come up with a song of their own that teaches them about manners. Give them a daily assignment to practice good manners at home.