The Anxiety Disorders Association of America reports one in eight children suffer from anxiety disorders. Without intervention, they're at risk for poor performance, diminished learning, and social/behavior problems in school. Because anxiety disorders show up differently in children, parents and teachers can't always identify them until the child hits the breaking point.

When a student acts out—throws a book, yells, storms out of the room—or has difficulty learning to read or grasping new math concepts, teachers often don't suspect anxiety as the underlying cause, which means the problems may persist or worsen.

This fall, I consulted with Mr. Lee, an exasperated third grade teacher. "I want to give up," he said, slumping in his chair. Mr. Lee is one of the most thoughtful, talented teachers I've worked with. It's unusual to see him so defeated. He related an incident from that morning's math class.

Mark was in a great mood. He loves math, especially math fact bingo, which was on the agenda for the day. As always, Mr. Lee asked Mark if he would like to pass out the pencils. Mark asks to do this almost daily because he says he "likes to get up and move." Today Mr. Lee had barely finished the question when Mark jumped out of his seat, swiped the contents of his desk on the floor, screamed, "I hate this school!" and ran from the room. "It came out of the blue!" Mr. Lee said.

"Out of the blue" behavior
When I hear a teacher report a student's challenging behavior "comes out of nowhere" or is "totally unpredictable," I begin to suspect anxiety. Teachers are trained to recognize behavior patterns ("Carl always gets frustrated during math," or "Maria often cries when asked to read aloud."), but some students with anxiety don't show clear patterns. Anxiety levels fluctuate throughout the day, based on many variables, making the student's behavior seem erratic. Think of an unopened soda can. You can't know if it's been shaken until you open it and it explodes. Similarly, it's difficult to see how shaken a student is in any given moment until he acts out.

When Mark was asked to pass out pencils on Monday he did it with a smile on his face. On Tuesday, he said "Great!" when asked. But on Wednesday he totally blows up. The outburst has little to do with distributing pencils. It's due to the high level of anxiety Mark was experiencing at the moment he was asked. On that day the request was the last straw.

Effects on Academics
This invisible disability can greatly affect academic performance as well. Anxiety impacts a student's working memory, making it difficult to learn and retain information. The anxious student works and thinks less efficiently, which significantly affects the student's learning capability. One study showed children who were the most anxious in the autumn of first grade were almost eight times more likely to be in the lowest quartile of reading achievement and almost 2.5 times more likely to be in the lowest quartile in math achievement by spring of first grade.

What's worse, academic performance can be hindered in an inconsistent way due to the student's fluctuating level of anxiety. This leaves teachers befuddled and left to make their own conclusions.

Mr. Lee expressed his confusion. "Yesterday Mark wrote three exceptional paragraphs and today he didn't finish a single sentence. Is he tired? Is he lazy today?"

This inconsistent presentation is unique to anxiety. Other disabilities, such as a reading disability, are much more predictable. A student with dyslexia doesn't read a chapter flawlessly one day and then struggle over a sentence in the same book the next day. Teachers aren't accustomed to thinking of disabilities as affecting kids only some of the time.

Recognizable Effects on Behavior
Without obvious signs, like sweating, shaking or blushing, anxiety is difficult to detect. The good news is that anxiety isn't always totally invisible. A teacher can learn to recognize the more elusive behavior signs— increased inflexibility, over-reactivity, emotional intensity, and impulsivity. Many anxious students try to escape or avoid something through behavior, for instance going to the nurse to avoid a math quiz or acting up to be kicked out of chorus. Just as with a child who has oppositional behavior disorder, reactions may be tantrums, constant arguments or angry and disruptive acting-out. The form the behavior takes isn't particularly distinctive—the only difference between oppositional and anxiety-related behavior is the underlying cause.

Educating teachers about anxiety and the behavioral signs they may see in the classroom makes this invisible disability easier to detect and understand. Mr. Lee learned to expect the unexpected while gaining an understanding of anxiety. The trained teacher is on the way to intervening effectively, turning the tide for the student's academic and behavioral performance.

This post originally appeared in The Huffington Post.