Here's a story that might turn the stereotype of "dumb jocks" on its head.
A review of earlier studies by Dutch researchers finds more physically active students tend to get better grades.
The researchers say they found a strong link between the amount of exercise school kids get, and how well they do in class.
It's believed physical activity increases blood flow to the brain, and that can help kids stay sharp.
The findings were published in this month's edition of the "Archives of Pediatrics and Adolescent Medicine."