Children, I think, should have some basic manners by the age of eight. 

Is this starting to sound like a lecture? Probably, but lets call it advise. It stems from the myriad scores of children that have roamed in and out of our home over the years. Here are some of the fundamental things children and in turn adults should do. When they enter a home, they should make eye contact and greet the host or hostess; an informal, "Hi Mrs. L. How are you today?" does the trick. They should be able to mount a staircase serenely, that means without charging, whooping or touching the walls....I have purchased a bannister rail from the builder for the purpose of holding onto. When they are fed a snack or a meal, they should thank the person feeding them. They should not ask for food or drink, except for water. By eight years of age, one should know how to use a knife and fork properly...in I guess, the European style. Fork in the left hand always, to bring food in bite-size proportions to the lips and knife in the right to cut food and guide it onto the fork. Someone may consider this snobbish,  I believe it is in fact a great equalizer. With this easy skill one can eat with kings or paupers and feel comfortable. Rows of cutlery should invoke delight, not dismay. I've taught all of my children and even my husband who asked me to when we were dating. Etiquette is a loss art, but it only enhances our ease and confidence when we seek to learn to improve ourselves.