In an organized school environment, children learn to do those things which will be required in adult life. This includes waking up in a timely fashion, keeping to a daily schedule, learning to take the commands of a superior and doing what they want done in an efficient fashion, completing paperwork and reports on time, managing relationships with peers, as well as cooperation and teamwork.
Meanwhile, all those spelling and geography bees won't mean diddly to the first boss, who simply wants the work done.