All children have some way of handling it when they don't get their way. They have their own ways of reacting when things do not work out as they want. They have ways of dealing with a world they think is sometimes unfair.
Two of their choices are temper tantrums and pouting. Most children use one or the other of these once in a while; and if you watch your child, you likely will see he uses one more than the other.
Just to be fair, answer this question. "When you get angry or frustrated, are you more likely to pout or have a little temper tantrum?" If you do not know or think you do neither, ask someone at your home what they think. They will quickly tell you whether you are a pouter or temper tantrum thrower.
Take a minute to think about a child who neither pouts nor has temper tantrums. This can be much worse than either pouting or temper tantrums because it often means the child is just accepting whatever happens. Even worse, he has gotten to where he no longer has any feelings about what happens to him. He does not care or thinks what he feels does not matter. This is a very unhealthy place for any child to be both emotionally and interpersonally.
What is your child doing when he pouts? He is angry, frustrated, or upset about something; but his predominate feeling is anger. He does not talk about it or try to work out his problem. Instead, he pouts and makes it rough for you and other people who are around him.
Think about what upset him. Maybe what happened was unfair and he really was treated badly. Either way, his pouting about it is a problem.
Based on your thinking about what might have set off your child's pouting behavior, you can say, "I've thought about what happened. We can talk about it if you want to. Here's my problem right now. You have a right to feel how you feel but pouting about it isn't your best choice. I think it'd be better if you either got up-and-over it or at least talked about it. It's your choice. This is what I'm going to do. I'm going to do nothing unless you choose to talk with me about it. You can pout or talk. It's your choice. If you choose to pout, please do it in your room." Now, leave it alone. His only choice is to behave more appropriately or be by himself.