These tidal-level forces interacted, and continue to interact, with changes
in the technology itself. At the simplest level, the content changes took
place in part because of the availability of machines that can perform computations
that were once done only by hand and some that are entirely
infeasible by hand. In addition, electronic media are interactive, which
means that a student's actions yield a reaction on the part of the machine,
which in turn sets the stage for interpretation, reflection, and further action
on the part of the student. Hence we can see an obvious interplay between
pedagogical tides that are moving toward increased student control of their
learning activities and the technological tide of ever more powerful computational
and graphic processing.