But whether preschool really helps your child depends in large part on how much you can afford to pay, according to the documentary. If you’re poor, your child can qualify for the free federal Head Start program. But some say the promise of the 35-year-old program has not been kept. A 1999 study found that children entered Head Start able to recognize only one letter and left a year later still knowing only one letter.

If money’s not a problem, you can enroll your child in a private preschool. You’ll find good teachers, many with master’s degrees, and a challenging curriculum. But you’ll pay as much as $15,000 a year.

And middle-income families — no surprise here — are stuck in the middle, neither wealthy enough to pay high tuition nor poor enough to qualify for free preschool.

“The Promise of Preschool” looks at three families — one wealthy, one middle class and one poor — to see how their children are faring. Coupling these families’ first-hand experience and interviews with early-childhood education specialists, the program offers a concise yet remarkably informative summary of where the nation stands in pre-K education.

As for Miller’s suggestion that we lop off the last year of high school and stick it onto the beginning of school … well, it’s a good sound bite, but is it practical? Kay Hymowitz of the Manhattan Institute doesn’t buy it. She says, “If we’re going to provide such wonderful preschools for our nation’s 4-year-olds, why haven’t we done that for our nation’s 5- through 17-year-olds?”

It’s a good question. Unfortunately, it’s one that no TV documentary can answer in 60 minutes. — Don Dale