Comparison is a dangerous word to use with students. It's not a good idea generally to compare kids' skills; it's doubly important to be cautious about measuring students with disabilities with the same stick that we use to measure general education students. It is the old "apples to oranges" scenario. What we can do is to examine all students and decide whether a disability exists and if so, how we can remediate. Read more at Comparing Special Education and Mainstream Students