“Obama says kids in the U.S. spend too little time in the classroom, putting them at a disadvantage when competing with students in other countries.”
This is actually a misconception.
While American kids spend fewer days in school, they spend more hours than even places like Japan.
Which if you combine the two facts seems to indicate that frankly a slightly longer school year (maybe 15 days) combined with a slightly shorter school day by an hour or so is the best solution.