The instruction we offer students, at any level, presumably reflects
what we believe will help them understand physics.  Physics instructors
do not typically subject their beliefs to scrutiny, working instead
from common sense assumptions about what students need clear
explanations, demonstrations, motivation and practice.  As in physics,
however, common sense ideas (e.g. 'objects move because they are
pushed') aren't always correct.  This talk will present evidence that
the usual assumptions are insufficient and offer an expanded set of
possibilities.