When a child is one year behind in mathematics or reading, it should be considered a content deficits.  Content deficits can be remediated with short term tutoring in a specific content area.

When a child is 2 years behind or more in a mathematics or reading, it is no longer a content issue, it is a cognitive skill deficit.  This means that there are underlying cognitive deficits which are causing the problems with reading or math.  These cognitive skills are the building blocks that allow the processes of learning, retention, and recall to occur.