push in math curriculum

Our district is going to be implementing a "push in" program with its new math curriculum. Students with learning disabilities will spend 1/2 hour in the general ed class, 1/2 hour with the resource teacher supporting the class lesson, and if that is not enough, they will be pulled out for another 1/2 hour per day for support. I have been told that this is a proven model, but have not seen research on it. Has anyone used this math model?