LA CHIRIPA, Mexico -- Teacher Blanca Isabel Banuelos instructs her pupils in semidarkness. The power has been cut to her one-room school for lack of payment.

Kindergarteners run about, damp with sweat in the languid heat of the village La Chiripa, set amid shrimp farms on the Pacific Coast. Without electricity, the fans can’t relieve the swelter.

“We need to have a fan working because the kids get hot,” Banuelos lamented.

Conditions aren’t much better at another dingy school nearby, where pieces of cardboard cover shattered windows, toilets rarely work and the sole computer broke down long ago.

When experts talk about Mexico’s future, they bemoan the condition of its schools. It’s here, they say, that Mexico’s possibilities of one day rivaling Europe as an economic power, something that would be an enormous benefit not just to this country but to the United States as well, founder.

It’s not that Mexico spends too little on education. Some 20 percent of government spending goes toward schools. “Mexico spends quite a bit,” said Lucrecia Santibanez, an education researcher at the RAND Corp., a nonprofit research group with headquarters in Santa Monica, Calif.

But a series of unusual – even bizarre – practices govern schools, with some 90 percent of the spending going to teachers’ salaries, leaving little for building and maintaining schools and for buying textbooks and computers. “There just isn’t a correlation between the spending and the quality of education,” Santibanez said.

In Mexico, teaching jobs routinely are bought and sold. In three of the country’s 31 states, teachers’ offspring can inherit their posts, with minimal vetting of qualifications.

The massive national teachers union, the largest trade union in Latin America, has wrested partial control of education policy from the federal government and it fiercely blocks reforms. At its helm is an astute union chief with a title that matches her autocratic style: “president for life.”

Even basic information on education eludes the executive branch. No one in authority seems to know the number of public school teachers in Mexico. The best guess is somewhere between 1.1 million and 1.3 million.

Far clearer is the poor performance of the nation’s 34.9 million primary and secondary students. International assessments show nearly half of Mexico’s 15-year-olds failing at all but the most basic skills in math and science. Mexico ranks last in educational achievement of the 34 countries that are members of the Organization for Economic Co-operation and Development, a forum of democracies with market economies. Far less than 1 percent of Mexican students excel at advanced math, behind students in Uruguay, Chile, Argentina and Brazil, according to the OECD’s 2009 assessment.

The crisis has physical manifestations in the nation’s 233,000 primary and secondary schools: leaky roofs, peeling paint, blackboards with cracks, schools with satellite dishes for distance learning but no electricity to run them. Even drinking fountains have run dry.

“Ninety percent of schools in Mexico do not have potable drinking water,” said Jorge Javier Romero, a political scientist and education expert at the Metropolitan Autonomous University in Mexico City. “Seventy percent don’t have a telephone. So how are they going to have Internet?”