You have just modeled a single grain, two grains with a grain boundary, and an amorphous
solid. These different arrangements of atoms on the nano-scale lead to some very different
behaviors of the materials on the large-scale. The grain boundaries you modeled are really much too
small to see with the naked eye, but they give the materials properties that we can test and use.
Amorphous solids (with no grain boundaries) have some pretty cool properties. Check out some of
the other activities in this section to learn more about crystalline and amorphous solids!