What is a discrepancy definition of reading disability? What are the advantages and disadvantages of a discrepancy definition?

Question

What will be an ideal response?

Answer 1

A discrepancy definition defines reading disability as a difference between a student's ability and reading achievement. Disadvantages of this definition include problems in defining and measuring ability and the fact that struggling readers might score low on tests of ability because their lack of reading skills has cut them off from a source of developing their ability. In addition, intervention might be delayed because it might take time for a large enough discrepancy to manifest itself. 
An advantage of the discrepancy definition is that it is logical to expect students to be able to read up to their abilities, so that this can be a useful gauge of a reading difficulty. Brighter students are expected to read above grade level whereas students with limited ability might not be expected to read at grade level.