But now there is growing concern that many of those children may be mis-diagnosed.
When Jonathan Coad was having trouble in school, his mother says first they thought it was attention deficit disorder. But then a speech therapist asked him to repeat a sentence.
"The sentence was the gray cloud covered the sun. He repeated the gray clown colored the sun," said Melissa Coad.
Jonathan was diagnosed with Auditory Processing Disorder or APD.
"Ears are very important of your body," said Jonathan.
They are important but with APD, hearing is fine. The problem is how that information is processed by the brain
"It means what the child hears might come in absolutely normally but as it transfers up it gets distorted or delayed ," said Lois Heymann.
Heyman is Director of Communication at the Center for Hearing and Communication in Manhattan. She says auditory processing disorder is often misdiagnosed as attention deficit disorder.
"It can be confused because if the child is not hearing it well and not processing it well their attention is going to change," she said.
And some kids, like Felix Telsey will have both APD and ADHD. But Lois says unless you address both- medications will not help. But the American Academy of Audiology has called APD a "controversial and highly charged topic" because it's not considered an official medical diagnosis.
That means insurance companies often consider the treatment and therapy experimental or investigational- and won't cover it.
If medical insurance does not cover the treatment, the Department of Education may cover it.