How do teachers help children understand the difference between the structure of a flower and that of a root? Depending on the time of year this activity is quite easy. Get a bunch of flowers, germinate some chickpeas and raid the kitchen for carrots and beetroots--the children can experience the "real thing". But what if teachers want the children to observe the orbits of the Earth and Moon, to see what intestines look like or to understand how particles in a solid are arranged? For these sorts of scientific topics, particularly the more abstract ideas, teachers cannot use the "real thing" and they use models to help explain the science. In this article, the authors explore why teachers use models in the classroom and why they need to reflect on the models' limitations with the children. (Contains 3 figures and 1 table.)