Underpinning science education reform movements in the
last 20 years—at all levels and within all disciplines—is an
explicit shift in the goals of science teaching from students
simply creating a knowledge base of scientific facts to
students developing deeper understandings of major concepts
within a scientific discipline. For example, what use is a
detailed working knowledge of the chemical reactions of the
Krebs cycle without a deeper understanding of the relationship
between these chemical reactions of cellular respiration
and an organism’s need to harvest energy from food? This
emphasis on conceptual understanding in science education
reform has guided the development of standards and
permeates all major science education reform policy documents
(American Association for the Advancement of
Science, 1989, 1993, 2001; National Research Council, 1996).
However, this transition to teaching toward deep conceptual
understanding often sounds deceptively simple, when in
reality it presents a host of significant challenges both in
theory and in practice. Most importantly, few if any students
come to the subject of biology in college, high school, or even
middle-school classrooms without significant prior knowledge
of the subject. It is no surprise, then, that students can
never be considered blank slates, beginning with zero
knowledge, awaiting the receipt of current scientific understanding.
Yet, there is often little time invested by instructors
in finding out in depth what students already know and,
more specifically, what they do not know, what they are
confused about, and how their preconceptions about the
world do or do not fit with new information they are
attempting to learn. In this feature, we explore key ideas
associated with teaching for understanding, including the
notion of conceptual change, the pivotal role of alternative
conceptions, and practical implications these ideas have for
teachers of science at all levels in designing learning
experiences for students.