• 6-8: 4D/M1a. All matter is made up of atoms, which are far too small to see directly through a microscope.
• 6-8: 4D/M1cd. Atoms may link together in well-defined molecules, or may be packed together in crystal patterns. Different arrangements of atoms into groups compose all substances and determine the characteristic properties of substances.
• 6-8: 4D/M3ab. Atoms and molecules are perpetually in motion. Increased temperature means greater average energy of motion, so most substances expand when heated.

• 6-8: 11B/M1. Models are often used to think about processes that happen too slowly, too quickly, or on too small a scale to observe directly. They are also used for processes that are too vast, too complex, or too dangerous to study.
• 6-8: 11B/M5. The usefulness of a model depends on how closely its behavior matches key aspects of what is being modeled. The only way to determine the usefulness of a model is to compare its behavior to the behavior of the real-world object, event, or process being modeled.

Check out this untraditional model for investigating the attractive interaction between neighboring atoms. Students explore chemical bonds as analogous to a stretched or compressed spring. Gently shaking the model shows how stored energy is released. Shake it vigorously and the model breaks....representing the breaking of chemical bonds.

• Physical Sciences K-8 Teaching Nanoscale Science Unit
• Physics First Teaching Nanoscale Science Unit