• 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: 4D/M3cd. In solids, the atoms or molecules are closely locked in position and can only vibrate. In liquids, they have higher energy, are more loosely connected, and can slide past one another; some molecules may get enough energy to escape into a gas. In gases, the atoms or molecules have still more energy and are free of one another except during occasional collisions.

• 6-8: 4E/M3. Thermal energy is transferred through a material by the collisions of atoms within the material. Over time, the thermal energy tends to spread out through a material and from one material to another if they are in contact. Thermal energy can also be transferred by means of currents in air, water, or other fluids. In addition, some thermal energy in all materials is transformed into light energy and radiated into the environment by electromagnetic waves; that light energy can be transformed back into thermal energy when the electromagnetic waves strike another material. As a result, a material tends to cool down unless some other form of energy is converted to thermal energy in the material.
• 9-12: 4E/H9. Many forms of energy can be considered to be either kinetic energy, which is the energy of motion, or potential energy, which depends on the separation between mutually attracting or repelling objects.

• 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/M4. Simulations are often useful in modeling events and processes.

• 8.F.2 Compare properties of two functions each represented in a different way (algebraically, graphically, numerically in tables, or by verbal descriptions).

• 8.F.5 Describe qualitatively the functional relationship between two quantities by analyzing a graph (e.g., where the function is increasing or decreasing, linear or nonlinear). Sketch a graph that exhibits the qualitative features of a function that has been described verbally.

• F-IF.5 Relate the domain of a function to its graph and, where applicable, to the quantitative relationship it describes.^?

This classroom-tested module features 8 interactive models for exploring atomic arrangements in gases, solids, and liquids. Highlight an atom and view its trajectory to see how motion differs in each of the 3 primary phases. Add heat energy to a system to watch molecular bonds break as molecules overcome their attraction. Editor's Note: This model is a very effective tool for visualizing the intermolecular attractions that underlie a phase change. Highly recommended.

• Physical Sciences K-8 Matter and Interactions Unit
• Physics First Matter and Interactions Unit
• Conceptual Physics Matter and Interactions Unit
• Algebra-Based Physics Matter and Interactions Unit
• AP/Calculus-Based Physics Matter and Interactions Unit

This classroom-tested module features 8 interactive models for exploring atomic arrangements in gases, solids, and liquids. Highlight an atom and view its trajectory to see how motion differs in each of the 3 primary phases. Add heat energy to a system to watch molecular bonds break as molecules overcome their attraction. Editor's Note: This model is a very effective tool for visualizing the intermolecular attractions that underlie a phase change. Highly recommended.

• Physical Sciences K-8 Properties of Matter Unit
• Physics First Properties of Matter Unit
• Conceptual Physics Properties of Matter Unit
• Algebra-Based Physics Properties of Matter Unit
• AP/Calculus-Based Physics Properties of Matter Unit