structional theory. Reigeluth ( 1983) suggests that instructional designers
require prescriptive instructional theory--a set of specific methods for
manipulating the instructional environment along with the conditions
under which each specific set of manipulations should be used to produce
a desired learning outcome. More importantly, he argues that a prescrip-
tive instructional theory may be independent of learning theory--the de-
scriptive theories do not need to consider the assumptions we are making
about the learning process and what it means to learn and understand.

As Carroll and Campbell have noted, our artifacts clearly reflect our
theory. Our designs are not just objective descriptions of the instructional
sequence, but rather they are also an implicit expression of our theory of
learning. Theories of learning and prescriptions for practice must go hand
in hand. Indeed, instructional designers often report that they have diffi-
culty getting the instructor to follow the instructional plan. We would
suggest that one of the reasons for this is that the instructor very likely
will have different goals for learning and a different concept of what it
means to "understand" the subject matter. That is, the instructor will
have a different theory of learning and will modify the instructional pre-
scriptions to accommodate that theory. Hence the instructor will seek to
supplement or replace content and strategies with approaches that he or
she feels will lead to the "appropriate" understanding of the subject matter
by the student.

Our commitment to theory-based instruction does not dispute the need
for prescriptions as frameworks for thinking about instruction. Nor are
we disputing the need for learning theories to provide a better description
of the instructional strategies or tactics implied by the theory. Indeed, one
of our goals in organizing this book has been to provide a firmer link be-
tween learning theories and instructional practices. We firmly believe
that prescriptions, along with a rich array of examples, form a foundation
for instructional design practices. They provide the base of ideas from
which designers can begin to develop their own plan for instruction in the
particular situation ( Duffy, 1990; Rowland, 1991).

Instructional design, and indeed instruction in general in the United
States, emerged from an objectivist tradition. Objectivism holds that the
world is completely and correctly structured in terms of entities, proper-
ties, and relations ( Lakoff, 1987, p. 159). Experience plays an insignificant
role in the structuring of the world; meaning is something that exists in
the world quite aside from experience. Hence, the goal of understanding is
coming to know the entities, attributes, and relations that exist. The objec-
tivist view acknowledges that people have different understandings based
on differing experiences. Indeed, because of prior experience it is unlikely

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