I'm not comfortable however in deciding what efficient teaching would be. One
very early preoccupation in education in North America dealt economy of time.
Around the turn of the century leaders of higher education created a committee
on the economy of time to decide who the school curriculum should relate to time
use. Out of that came integrating within fields: language arts, social studies,
science etc.
Efficiency of course is related to the goals of education. In a transmission
model it likely to seem efficent to teach a heirarchy of skills or a sequence of
facts directly and linearly. In a constructivist model eficiency looks quite
different.
Ken Goodman