MEXICO CITY — Many Mexicans reacted with shock and dismay when it was announced recently that nearly 70 percent of teachers had flunked a new nationwide test to measure whether they had the basic skills to be educators. I, for one, celebrated the news.

What is taking place in Mexico may be part of one of the most encouraging — and under-reported — trends taking place in Latin America.

For the first time, Mexico has begun to demand that all teachers who apply for new openings at public schools undergo a nationwide test. And the dismal results of the first such exam of 71,000 teachers on Aug. 11 has led the country to come to grips with the depth of its educational crisis.

Until now, Mexican teachers got their jobs by virtue of almost anything but their academic knowledge or teaching skills.

Teachers in public schools were appointed by the powerful National Teachers Union, often taking into account their political loyalties, or bought their jobs — which guaranteed lifetime employment — for about $5,000.

Not surprisingly, Mexico scored 29th among 30 countries in a recent Organization for Economic Cooperation and Development test measuring reading, math and scientific skills of 15-year-olds.

But earlier this year, following similar experiments in Chile and other Latin American countries, the government signed an agreement with the teachers union to start testing all teachers applying for new jobs in public schools.

Under the deal, known as the Alliance for the Quality of Education, all new teaching positions from now on will be filled by teachers who have passed the test, in the order of their respective scores.

Jorge Santibanez, a senior Mexican education ministry official who supervises the program, told me that Mexico has more than 1 million teachers and about 45,000 new job openings for teachers a year. This means that every year, nearly 5 percent of the teachers will join the school system after passing the exam, which would allow a gradual improvement of teachers' quality over the next 20 years.

"But we can't afford to wait that long," Santibanez said, "so we are proposing to give remedial courses to existing teachers and that they pass a certification process over the next few years.

"We are proposing to re-train about 150,000 teachers a year," he said. 'Adding together the newly hired and the re-trained teachers, we hope to renew the country's teachers' workforce within the next seven years." But is the teachers union going along with that?, I asked.

Like most other Latin American countries, Mexico has a politically powerful teachers union that, until now, successfully resisted any government efforts to reform the school system. Santibanez said that "we have reached an agreement in principle" with the union to go ahead with the certification process.

How did the government get the teachers union to agree to these reforms? I asked other Mexican officials and academics.

Most responded that the union had little choice but to negotiate, following growing public dissatisfaction over Mexican students' poor results in standardized international tests. Longtime teachers union leader Elba Esther Gordillo has political ambitions and cannot afford to be seen as the cause of Mexico's educational backwardness, they said.

The teachers union and its members, in turn, also are getting something from the recently signed Alliance: a government promise to rebuild or repair 30,000 schools around the country that have structural problems or lack such basic things as blackboards or chairs.

International education experts say Peru, Colombia and El Salvador also have begun to carry out similar teacher evaluation tests.

"It's an emerging trend," says Jeff Puryear, a Latin American education specialist with Inter-American Dialogue in Washington. "It is potentially very significant because it amounts to quality control for teachers, which most Latin American countries never had." My opinion: Granted, the Mexican teacher tests' results were abysmal. And the recently signed government agreement with the teachers union would have been much better if it also had included ruling party and opposition leaders, to ensure the program's survival in a region where new presidents often undo whatever their predecessors did.

But instead of shaking our heads in disapproval over the fact that so many teachers flunked the test, we should celebrate the fact that for the first time Mexico and other Latin American countries are recognizing the poor quality of their school systems and are doing something about it.

Andres Oppenheimer is a Latin America correspondent for the Miami Herald; e-mail: aoppenheimer@miamiherald.com.