Children at Oakdale School here in southeastern Connecticut returned this fall to learn that their traditional recess had gone the way of the peanut butter sandwich and the Gumby lunchbox. No longer could they let off youthful energy — pent up from hours of long division — by cavorting outside for 22 minutes of unstructured play, or perhaps a vigorous game of tag or dodgeball. Such games had been virtually banned by the principal, Mark S. Johnson, along with kickball, soccer and other “body-banging” activities, as he put it, where knees — and feelings — might get bruised. Instead, children...