The Institute says the 'culture of sports' discourages kids from reporting head injuries, and encourages them to get back to play too soon.
Some doctors say it's becoming clear many injured athletes aren't even ready to come back to school after a concussion.
Dr. Rick Figler, a sports medicine specialist, says in his practice, "What we find is they can go through first period, they feel fine. They go through second period, it might be a little more challenging, and they start to get their symptoms."
"They back off, they kind of put their head down," he continues.
Dr. Figler says kids who are concussed may have trouble learning new material, or remembering what they've learned.
The institute says there's been little research on concussions in kids - even though high school athletes suffer more of them than their college counterparts.
Football, ice hockey, lacrosse, wrestling, and soccer have the highest rates of reported concussions for males at the high school and college levels.
Soccer, lacrosse, and basketball have the highest rates of reported concussions for females at those levels.
Women's collegiate ice hockey has the highest concussion rate.
The Institute says coaches and parents shouldn't think helmets are sure-fire protection.
It said there's little evidence that helmets, face masks and mouthguards cut down the risk, though it said they DO prevent other injuries.