Using the Growth Model in Small Schools

I'm wondering what the value of the growth model is for small schools in Massachusetts. The principal of a school with less than 200 students has begun to analyze growth model data, and finds few surprises. He's unable to compare classes of students at grade levels because the school has only one class per grade, a situation that's common in our rural schools. He did look closely at a student whose growth percentile was extremely low, but he would have examined that student's progress anyway, because that student's scores had moved from advanced to needs improvement. I suggested that the growth model could provide a way to gauge the progress of students in groups that have traditionally had low performance levels on the MCAS, in this case, students identified with special needs. But the number of students is so small that their scores can be tracked and compared by hand!

So what is the value of the growth model for small schools?