"A useful distinction in the discussion of student characteristics is trait versus state. Traits are student characteristics that are relatively constant over time...whereas states are student characteristics that tend to vary during individual learning experiences, such as level of content-specific knowledge."
(Reigeluth, 1983, p. 32)
Reigeluth also states that "many strategy components have been shown to help students with all kinds of traits to learn" [p. 32]. My position is that we do not know a priori which aspects of our instructional strategies, learning environment, motivator, etc... will generalize across many or all students. However, with a localized learning theory we can learn over time which do and which do not. At the same time, we will likely find ways of grouping students that we never would have before imagined.