construct knowledge in science. They might know something about the objects they encounter in their everyday lives, but their experience with other materials or the transformation of materials is still limited. For example, they may deny that an object broken into tiny pieces is still the same kind of stuff because it no longer “looks like” the same stuff. Many of the most enduring and essential characteristics of materials (such as density, boiling and melting points, thermal and electrical conductivity, and solubility) are unknown to them.
Also, young children’s understanding of the material world is based on their perceptual experiences—on what they can see, feel, or touch. For example, they think of weight as something that they can feel with their hand. They may think, for example, that a piece of Styrofoam weighs “nothing at all” because it seems to exert no force on their hand. They rely on how heavy something feels because they have not yet differentiated weight and density.
While children may have amazing skills and capabilities to learn science, people do not spontaneously generate scientific understanding. The development of early ideas about matter, in which neither mass nor volume is considered a defining property, into a sophisticated understanding of atomic theory clearly requires formal academic instruction. Nor do people spontaneously generate deep scientific understanding of other core domains. The theory of evolution, for example, although fundamental to modern science, can be quite difficult to understand. Many children and adults embrace erroneous beliefs about evolution.
The complexities of science and science learning are real. To acknowledge this is to also concede that good science teaching requires extensive teacher knowledge, excellent curriculum, effective systems of support and assessment, and much more time and attention than are currently devoted to it. This can be daunting.
While the complexity of science poses significant instructional challenges, the interrelatedness of science makes it possible to focus and simplify curriculum and instruction in another important way. Science can be organized instruction around a small number of concepts. These “core concepts” have great explanatory power and can be built on in increasingly complex ways from year to year. In the next chapter, we’ll see how this process can work, not only for atomic-molecular theory but also throughout the disciplines of science.