Double blocks of Reading or Mathematics are common scheduling strategies in schools for those kids behind where they need to be. Studies suggest that when we do this we can boost the work of students’ achievement in Reading and Math when more time on task is used in productive ways. Other studies suggest that we should not take away time in Physical Education or “Recess”.
One study I would suggest is nicely reported on in the NY Times. Exercise (and from the review of some studies–vigorous exercise) contributes mightily to cognitive development, academic performance, and other means to student achievement.
Find the report on the study mentioned at: