IMO, anything below I40 is just bright and the child should not get differentiated instruction. The curriculum for all classes should be raised 1-2 years so that we don't have every other child reading past grade level. Children of non-English speakers need to be the ones removed from the mainstream classes so that they can get better instruction and so that they don't pull down native speakers and make them appear gifted.
differentiation is not just for gifted students. the idea is that all kids will get what they need at their level. ideally, differentiation would occur in every classroom to meet the needs of every student- low or high....not just the super smarty pants kids. when differentiation is done correctly, EVERY student benefits. if you had a kindergarten student who knew the entire alphabet, but was not gifted, they should not be made to sit through the entire letter b lesson just because they don't have an iq over 140.
