While the U.S. is preoccupied with terrorism, the listless economy and Lindsay Lohan’s latest rehab, another problem may loom larger in the long run: the decline of America’s once pre-eminent public education system.

That’s the message of Davis Guggenheim’s documentary “Waiting for Superman.”

The U.S. is ranked near the bottom among 30 developed countries in math and science, even though per-student spending has doubled over the last 40 years. Nothing illustrates the problem better than Guggenheim’s vignettes of students from neighborhoods with horrible public schools. They enter lotteries to get into superior charter schools, but there are so few openings that the odds are stacked against them.

The quality of education shouldn’t depend on where a child lives or a lucky number. America can’t afford that gamble.