One child watches another take a toy. The first child says, "I'm going to tell on you." The fact that he thinks he will gain a reward for this shows that he is in the _____ stage of morality.
There are 5 stages of moral development in children. Reading the example above, the child is in the 4th stage of morality where in he starts to think what would likely to profit him the most. On this stage he has a strong sense of "should do and should not do" and the thought of what's in it for her/him. Healthy negotiations between parents and the child also happen on this stage.