William Damon' first stage of friendship development deals with child ages from 4-7. They based they friendship on other behavior. Children see their friends just how they see themselves. It is sometimes called a handy playmate. For instance, kid1 likes to play barbie doll. Kid2 likes to play barbie doll so kid1 is a friend of kid2.
Answer:
They are useful because charts explain what numbers and etc things are.
Explanation: