As much as I agree with HK's main point, I do have a small quibble--I have actually seen many teachers lump all the -2 SD kids together. (For example, insisting that a child with an IQ below 60 couldn't possibly read independently, when, in fact, that child could decode beautifully at grade-level--comprehension was another question, of course. Many of them do have splinter skills, just as 2e learners, in the other tail, can have focal deficits. This can create a similar dynamic of simultaneously excessively high and excessively low expectations.)
But yes, teachers expect substantial modification to the curriculum to address the needs of a -2 SD student, but not for a +2 SD --or much more-- student. And the field has had subclassifications for -2 SD and beyond for decades (mild, moderate, severe, profound), but can't come to an agreement on +2 SD and beyond, nor teach the descriptive categories to even special ed teachers.
And just musing about the criteria for special education (as they apply to GT): a) a documented exceptionality (a disability, for traditional special ed), b) inadequate educational progress (for GT, it would be access to appropriate educational progress), c) need for specialized instruction, which means changes to content, methodology, or delivery of instruction.
