If the United States lagged behind other nations in defense capabilities, there would be a national uproar over how far the U.S. is falling behind and how the gap poses a security threat. But the lagging figures being talked about this week involve education.

The United States ranks near the top in per-student spending, landing in the fifth position. But it ranks way down the list in student proficiency, 21st in science literacy among 30 developed nations and 25th in math literacy.

These figures clearly show that something is wrong in public education — and something has been wrong for a long time.

Trends in U.S. education are not encouraging. Time magazine, which devoted much of its most recent issue to education, notes, "The U.S. since 1971 has more than doubled the money it spends per pupil, yet still trails most other rich nations in science and math scores."

President Barack Obama sees this also, saying the education crisis requires new ways of doing things, and adding, "We can't spend our way out of it."

This week, talking about needed changes in public education, Obama repeated his support for a longer school year to compete with other nations whose children spend more days and longer hours in school.

Public education and the many challenges facing students, teachers, parents and school districts is the subject of a new documentary film titled "Waiting for 'Superman,' " by Davis Guggenheim, the filmmaker behind "An Inconvenient Truth."

The first thing that becomes clear about fixing public education in America is that there is no Superman, and no silver bullet. It's more about innovation, about doing things in different ways, learning from the best teachers, removing the worst teachers, and insisting on accountability across the board.

Too much of education is designed for the convenience of adults. For instance, the short school day and long summer vacation are perks for teachers, but they do not help students — even if they too enjoy the light schedule.

There is growing agreement that American students need to spend more time in school. The standard 180-day school year lags well behind the average 196-day school year in countries whose students outperform their U.S. counterparts.

Frustration with lack of progress in many public schools appears to be cresting, and there is a growing group of reformers, including philanthropists like Bill Gates, through the Bill and Melinda Gates Foundation, and others pressing for real change.

Even Obama, who as a Democrat enjoys the support of teachers unions, is pushing, along with Education Secretary Arne Duncan, for change by offering billions of dollars in federal grants to schools that implement accountability for teachers and plan other changes in the "Race to the Top" competition.

Teacher evaluation is a part, but only a part, of the solution. It's critical to identify the best teachers and reward them, as well as using them as mentors to help other teachers improve. It's also important to identify the weakest teachers and first offer them help to improve, but if they do not improve, remove them from the classroom.

Teachers unions generally fight any effort to evaluate teacher effectiveness. But parents and anyone else concerned about education knows some evaluation is needed to improve the system. Teachers unions need to become less resistant to change or they will continue to lose popular support. Time's article notes, "Teacher unions have a long history of working against the interests of children in the name of job security for adults." While true of organized labor, many individual teachers would certainly challenge that perception.

Schools of education will have to change also and elevate their standards. Time's article points out that "23 percent of new teachers come from the top third of their college class; 47 percent come from the bottom third." In other leading countries, like Finland and South Korea, where students outscore U.S. students, 100 percent of teachers were in the top third of their college class.

Tenure is another area ripe for reform. In the United States, tenure is often granted after only a few years on the job, and essentially guarantees lifetime job security. Most reformers believe the standard for tenure should be more rigorous. In New York City, Mayor Michael Bloomberg announced reform plans that include a teacher evaluation and rating system along with a policy that will only award tenure to teachers rated "highly effective" or "effective."

In most school districts, receiving tenure is not part of a rigorous process. Without an effective evaluation system in place, it's a rubber stamp that robs tenure of meaning.

Still, it's worth remembering that teachers have a critically important job and face sometimes seemingly overwhelming challenges. All the more reason to have the best, most-effective teachers in every classroom.

Education reform has been simmering for decades; it now appears about to bubble over. Most Americans know it's critical to make changes to improve the U.S. public school system, to ensure that this country remains competitive with the rest of the world.

Education is an issue of economic security and future prosperity. And no issue facing America is more important, even if others appear to get more attention.