And we're not just talking high school students; this practice of hovering often begins before they've learned how to write. Kids used to grow up in a neighborhood-- on the block or in the parks, playing games with other kids. These games had rules, but the kids themselves determined them, flexing their imaginations. Social scientists called these activities -- capture the flag, bike races, pickup baseball games -- "free play, " and it's been steadily decreasing since the 1950s. Scientists have also noted a correlation between the decreasing amount of childhood free play—any play not directed by adults—and the increasing rates of anxiety and depression among kids. As free play decreases, anxiety increases.