Students know scientists have developed instruments that can create discrete images of atoms and molecules that show that the atoms and molecules often occur in well-ordered arrays.

Nobody in K-8 schools is expected to understand how these images are created. It is enough to simply be aware that scientists can create images of atoms and molecules, and that these images reveal that atoms can arrange themselves in a pattern of well-ordered arrays.

One connection that you can make with other standards in this set is that these images are made of substances in the solid state. Atoms and molecules in liquids and gases move around so fast that scientists cannot create images of them. In solids, the atoms and molecules remain in the same place much more than in liquids and gases. For the same reason, these images are often made with frozen samples where the atoms and molecules are moving much slower than at room temperatures.