Teaching our kids basic good manners is a process closely tied to their development. From your instruction and example, they establish a basic understanding of how they should interact with people and behave in a variety of situations.
Do your children have testamentary guardians? Have you appointed someone to take care of them if you die and are no longer around? Nobody ever wants to think about themselves dying, least of all parents of small children, but it can and does happen, and it can be really hard for children if there is no plan in place.