Being a mother it is very necessary to understand your kid's emotion. So some common emotions expressed by children are:
Anger
Children show anger when they fail at a task or non-fulfillment of wishes. They express anger by screaming, hitting, throwing and breaking things or holding of breath..
Jealousy
Children tend to feel jealous when there's an arrival of a new child in the family or if there is unfavorable comparisons made by the family. They express emotions by removing the anger on the rival, thumb sucking or nail biting.
Fear
Some children have fears of animals, people or darkness. They express fear by crying, tension, change in facial expressions or bed-wetting.
Affection
When children get attention from parents or teachers, they express it by hugging, holding hands or sitting nearby.
Happiness
Children express happiness when they are praised by elders or receive gifts. They express happiness in ways like smiling, laughing and clapping.