264 N. Valanides and C. Angeli
tools provide scientists with new ways for creating theories, testing ideas, and ana-
lyzing data. Scientists make observations, identify patterns in data, and then develop
and test explanations of these data using scientific models. Certain aspects of the
nature of science that are directly related to the use of models are tentativeness
and the need for continual revision and evaluation. Models and modeling activities
in science should include and cultivate the tentativeness of models, the role that
creativity plays in building models, the iterative aspect of modeling, and the fact
that scientists can have more than one model representing the same phenomenon or
object.
Model-based teaching constitutes a process of constructing mental models
of phenomena by coordinating resources of information, learning activities, and
instructional strategies, so that mental model building both in individuals and
in groups of learners is optimally fostered. Constructing mental models through
instruction can turn out to be a process of conceptual change associated with the
corresponding difficulties. In most cases, l earners’ pre-existing intuitive models
encompass their preconceptions and natural reasoning skills present before instruc-
tion (Clement, 2000) that cannot be observed directly. Thus, learning approaches
that can challenge students’ conceptual ecology and take them from preconceptions
to accepted consensus models following in most cases different learning pathways
(Niedderer & Goldberg, 1995), or a sequence of intermediate steps, should be
carefully designed and implemented. Hestenes (1996) stated that there are many
reasons for using models in science teaching, such as (1) model construction pro-
vides an interactive environment for student engagement leading to significant
learning gains; (2) working with models can enhance system-thinking abilities; (3)
model development is useful for helping students to develop skills in graphing and
mathematical computation and visualization; and (4) models can enable students
to run experiments or simulations using different assumptions without any harmful
consequences.
Computer modeling can also make scientific material more accessible and
interesting. For example, computer microworlds offer students access to worlds
that cannot directly experience and create a sense of owning and directing the
dynamics of these worlds (diSessa, 1985; Papert, 1980). Computer models can
also facilitate the processing of complex data, make the scientific process more
dynamic, and provide ways for studying interesting and complex phenomena.
Additionally, many computer-modeling tools, such as MARS, Model-It, STELLA,
and ThinkerTools (Metcalf, Krajcik, & Soloway, 2000; Raghavan & Glaser, 1995;
Raghavan, Sartoris, & Glaser, 1998; Stratford, 1997; White, 1993), when appropri-
ately used, can promote subject matter understanding, inquiry skills, and systems
thinking (Richmond, 2001).
Undoubtedly, pre-service and in-service teachers should develop an understand-
ing of the nature of science, including the knowledge that scientists formulate, and
test explanations of the nature of science using, among other things, theoretical
and mathematical models. De Jong and Van Driel (2001) stated that pre-service
teachers lack knowledge about the use of models in science and that there is a
pressing need to engage all prospective teachers in rich modeling activities so
that they become able to use models in science teaching and learning. Smit and