Some signs of abnormal behavior are:
Difficult time managing emotions, a child who can not control their anger or frustration.
Difficult time managing physical aggression
Behavior that do not response to discipline which is normally child who misbehave over and over to get an reaction or discipline from their parents.
Self- Injury, a person who may hurt themselves
Behavior that relates to social reaction, have a hard time making friends
Behavior that relates to school setting, some actions that affect child education