MIAMI (AP) — As school districts across the nation begin evaluating teachers based on student growth, one area is posing a unique challenge for administrators: special education.

Special education students have a range of conditions that can affect their intellectual growth significantly or not at all. For those with most profound disabilities, measuring growth based on testing can be extremely difficult.

Teachers like Bev Campbell in South Florida say growth for these students is often measured in small steps.

Spurred by the U.S. Department of Education’s Race to the Top competition, more than a dozen states have passed laws reforming how teachers are evaluated and including student growth as a component. Now officials in states such as Florida, New York and Illinois are trying to meet deadlines to evaluate teachers on those criteria.