is drastically different in just 25 - 30yrs. We used to have a 15 min outside break in the Am and Pm plus a 1/2 hr after lunch (so 1hr off of study and in seats). And not a bit of it effected our learning or comprehension. We always had good test scores on those assessments which used to be a teacher/ student/ parent help aid along with the school work we did in the classroom.
Now, they have so little time outside to just let loose. And really, kids that age have about 15 to 20 mins where they can focus and learn and retain. After 30mins, they won't retain it. Focus isn't that long for young children.
I happened to go to a small school that went up to 8th grade and we all got that same break time away from our desks, time to talk and chit chat, and just have a good brain break in between subjects. It seems insane how we are subjecting our young children from being young and having imagination and free time to think and have time to hang out with friends and run around a bit, into monotone drones.