This question is often asked by those considering educational alternatives. But it makes some faulty assumptions, and the first one is that there is a "normal." The human brain is the most complicated structure in the universe that we know of, 100 billion of neurons with 100 trillion of connections--all in positions unique to that individual. Each brain develops on its own time schedule; first one area and then another, depending on the child. Pushing a child to catch up to where the teacher wants him to be is not helpful, and can be harmful.
Second, research has shown that everything a child learns under the age of 12 (or so) can be learned by a child over the age of 12 in nine month or less. Which begs the question: why do they need to spend 1260 hours each year sitting in a classroom? They could be running through the wet grass and looking at bugs and following their own interest. They SHOULD be developing their own interests as they see fit.
Most parents worry about their children feeling dumb if they realize, at church or Scouts, that others have reading or math skills that they don't. By spending 1/2 hour per day in the young years on academics, you've still got 23 1/2 hours per day to play and explore. My children all responded well to this approach, gaining the skills to "keep up with the Jones's" while maintaining their love of learning. It's a pretty good trade-off.
