The Education Department is requiring the state of Arizona to offer language instruction to tens of thousands of students who are not proficient in English.

A federal civil rights investigation found that 42,000 students were misidentified as "Proficient in English."

As part of what's being called an intervention plan, those students will receive special reading and writing classes to bring them up to speed.

They were either not put in those classes when they should have been, the investigation found, or were moved out of them too quickly.

Arizona schools won't get any additional money to offer the classes, and they'll have to create new criteria that correctly identifies students who need English language services.