However much we all might wish that great teachers leveled the playing field and brought every student up to impressive levels of achievement, this paper suggests otherwise: Bad teaching hinders all students, and good teaching helps all students– just not necessarily by the same amount or to the same level. It also contradicts the notion that capable students just teach themselves and don’t need good teachers.
Quite simply, good teaching helps all students reach their potential.
This also implies that we should be careful in how we measure achievement gaps: Variability in meeting basic skill levels (which we may reasonably expect of all students) is problematic, but overall variability (in reaching higher levels of achievement) may actually be a sign of good teaching.
(Full article available via subscription at http://www.sciencemag.org/cgi/content/full/328/5977/512?rss=1.)