It is a mitzva incumbent upon parents to teach their children Torah and to train them to keep the mitzvot. The more a child’s understanding develops, the more Torah we teach the child. With observance as well, we teach children to perform any mitzva they can understand. By around age six, a child can start to learn seriously, and this is why children start school at six. When dealing with prohibitions, the rules are different. Even before children can understand what is prohibited, the parents are not allowed to cause them to sin (for example, by feeding them non-kosher food).
It is a mitzva for parents to educate their children to live a life of Torah, develop positive character traits, and engage in considerate behavior. True, teachers can reinforce what the parents teach, but the overall responsibility for educating children remains with the parents.
Personal example is the foundation of all education. Children often emulate their parents, so it is important they see their parents are content with what they have; love Torah and care about mitzvot; contribute to the world; do not chase after luxuries or awards; are happy with their friends; help others, and are considerate and respectful of everyone. Parents should also listen to their children talk about anything bothering them, and teach them how to interact with their friends. Of course, parents must also project a very positive attitude towards school. They should send the children off to school happily, encourage them to study, follow their progress, and communicate with their teachers. Parents should also share their faith and the values by which they live their lives. This can instill the children with faith in God and in their special mission, so when they grow up, they will be able to choose the best path to utilize their talents and improve the world.