Every so often I’ll have a student who says they’re not very interested in learning English because they’re going back to Mexico as soon as possible.

My usual response, which has been pretty effective, is that the student is likely to get a better-paying job there if he/she knows English, too. That position makes sense to me and, usually, to the student, who then tends to become more serious about learning English.

I have gotten anecdotal evidence from English teachers in Mexico that this statement is true, but I’d love to find some data showing it is.

Can anybody help me out?