  Learning to create, use, and evaluate models is a central element of becoming
a scientist. In physics, we often begin an analysis of a complex system with
highly simplified or toy models. In introductory physics classes, we tend to
use them without comment or motivation. Some students infer that physics is
irrelevant to their understanding of the real world and are discouraged from
making the cognitive blend of physics concepts with math symbology essential
for making sense of physics. In this paper, I discuss the often hidden barriers
that make it difficult for our students to accept and understand the value of
toy models, and suggest instructional approaches that can help.
