There is no disagreement about the importance of understanding the structure of matter. Richard Feynman, a famous Nobel prize-winning physicist, has said:

If, in some cataclysm, all scientific knowledge were to be destroyed and only one sentence passed on to the next generation of creatures, hat statement would contain the most information in the fewest words? I believe it is the atomic hypothesis (or atomic fact, or whatever you wish to call it) that all things are made of atoms-little particles that move around in perpetual motion attracting each other when they are a little distance apart, but repelling upon being squeezed into one another.

Teachers should assess students’ knowledge prior to instruction of this topic, as the atomic theory of matter may be very challenging to them. Students are expected to recall terms and definitions from earlier introductions to the concepts of atoms, molecules, and elements. Instruction should provide empirical evidence for the atomic theory, which will be useful for understanding science and crucial to the study of chemistry.

When students learn about the structure of matter, teachers should emphasize that the historical evidence for atoms was based largely on indirect measurements and inferences far removed from direct experience. Recently, instruments have been built that produce images of individual atoms, confirming what was inferred earlier as a result of overwhelming evidence from many scientific experiments. Most scientists come to know the atomic theory is true by repeatedly using the concepts and principles presented in the theory to explain observed properties and predict changes in matter.