Children should be taught to say "please" and "thank you" at the appropriate moments, according to Education.com. It's also important to teach children to wait their turn, speak respectfully to others and respect the belongings of others. Most children can grasp these simple manners by preschool age, but it may take until the age of 9 or 10 for manners to be fully ingrained.
A child should learn to say "please" when asking for something and "thank you" when something is done for her. These are some of the earliest manners that a child can be expected to master. In some families, children are taught to call elders "ma'am" or "sir."
It is also important to teach a child to wait patiently when necessary. That means standing quietly in line, waiting for a turn with a toy, and letting other people exit a room or elevator before pushing her way in. She should also learn to say "excuse me" when she needs to get someone's attention.
Teach a child to ask before taking a friend's toy and to treat other people's things carefully.
Mealtime manners also need to be taught. Remind a child to keep her elbows off the table and chew with her mouth closed. Demonstrate how to ask for an item to be passed, rather than reaching across someone to grab it.