The programs aren't substitutes for U.S. curricula, but educators familiar with them say they provide a lifeline for adult students with little formal education by helping them become literate in Spanish — and by extension, English.

Yet many educators are wary of even talking about the programs, fearing they might stoke an anti-immigrant backlash.

The Mexican government, which spends more than $1 million annually on the programs, has many reasons to provide the aid to the immigrants and their children. The programs allow it to give back to the growing number of Mexicans living legally and illegally in the U.S. Behind oil, remittances from these individuals are the second-largest source of foreign income for the Mexican economy — almost $24 billion last year. ....