In the art room at P.S. 188 in Bayside, Queens, a group of 9-year-olds was busily putting the finishing touches on an enormous poster for the fourth-grade play. Its topic: saving the Earth. Down the hall in the music room, beneath portraits of Mozart and Bach, classmates were breaking into a spirited rendition of “Hear Those Bells” on fluorescent-colored recorders. Cheerleaders in the gym were perfecting a victory chant, jumping, twisting and stamping their feet. And in the library, children in a Suzuki violin class were toiling away at “Twinkle, Twinkle, Little Star,” while their music teacher, a professional violist from Iceland, coached them “to stand straight and tall.”

All of this concentrated learning — activities parents commonly think of as enrichment — was taking place not after school hours, but during recess, the once-unstructured midday break that for some elementary school students is slowly being squeezed out of the day.

Jump rope, freeze tag and the jungle gym have some new competition. At some of the city’s highest-rated public elementary schools, recess is now being seen by parents and educators as a time to pack in extra learning.

Free time during school hours has become a hot topic among educators across the country, many of whom worry that children are not getting enough of it. Recent studies, including one published in 2009 in the medical journal Pediatrics, indicate that many children learn better and behave better when free time is part of the school day.