Kids who spend a lot of time outdoors not only tend to be healthier, they see better. That’s the conclusion drawn from a recent Chinese study of kids in first-12th grades.

Scientists followed a bevy of children for three years. Some of the kids were given an extra 40 minutes of outdoor school time, and researchers asked these same kids (with some encouragement from their parents) to spend more time outside during their non-school hours, too.

A little more than 30 percent of these outdoorsy children were nearsighted by the end of the three-year study—significantly less than the nearly 40 percent who turned out nearsighted in the control group. (Time)