Caroline Miller from the Child Mind Institute has written a good article for parents and teachers about how Anxiety Leads to Behaviours.  An excerpt:

Anxiety manifests in a surprising variety of ways in part because it is based on a physiological response to a threat in the environment, a response that maximizes the body’s ability to either face danger or escape danger. So while some children exhibit anxiety by shrinking from situations or objects that trigger fears, some react with overwhelming need to break out of an uncomfortable situation. That behavior, which can be unmanageable, is often misread as anger or opposition.

“Anxiety is one of those diagnoses that is a great masquerader,” explains Dr. Laura Prager, director of the Child Psychiatry Emergency Service at Massachusetts General Hospital. “It can look like a lot of things. Particularly with kids who may not have words to express their feelings, or because no one is listening to them, they might manifest their anxiety with behavioral dysregulation.”

The more commonly recognized symptoms of anxiety in a child are things like trouble sleeping in his own room or separating from his parents, avoidance of certain activities, a behaviorally inhibited temperament. “Anyone would recognize those symptoms,” notes Dr. Prager, co-author of Suicide by Security Blanket, and Other Stories from the Child Psychiatry Emergency Service. But in other cases the anxiety can be hidden.

You can read the full article here on childmind.org.