• 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: 4D/M7a. No matter how substances within a closed system interact with one another, or how they combine or break apart, the total mass of the system remains the same.
• 6-8: 4D/M8. Most substances can exist as a solid, liquid, or gas depending on temperature.
• 9-12: 4D/H8. The configuration of atoms in a molecule determines the molecule's properties. Shapes are particularly important in how large molecules interact with others.

• 6-8: 4E/M4. Energy appears in different forms and can be transformed within a system. Motion energy is associated with the speed of an object. Thermal energy is associated with the temperature of an object. Gravitational energy is associated with the height of an object above a reference point. Elastic energy is associated with the stretching or compressing of an elastic object. Chemical energy is associated with the composition of a substance. Electrical energy is associated with an electric current in a circuit. Light energy is associated with the frequency of electromagnetic waves.
• 9-12: 4E/H7. Thermal energy in a system is associated with the disordered motions of its atoms or molecules. Gravitational energy is associated with the separation of mutually attracting masses. Electrical potential energy is associated with the separation of mutually attracting or repelling charges.
• 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.

• 6-8: 11D/M3. Natural phenomena often involve sizes, durations, and speeds that are extremely small or extremely large. These phenomena may be difficult to appreciate because they involve magnitudes far outside human experience.

This lesson plan with student guide was created by a high school teacher to accompany the PhET simulation States of Matter. It's intended for students who already have some knowledge of basic kinetic molecular theory. It provides guided exploration of particle behavior as it relates to phase, molecular polarity, force interactions at the molecular level.

• Conceptual Physics Matter and Interactions Unit
• Algebra-Based Physics Matter and Interactions Unit
• AP/Calculus-Based Physics Matter and Interactions Unit

This lesson for high school physics or chemistry was developed specifically to accompany the PhET simulation States of Matter. It guides students in an exploration of particle behavior as it relates to phase, molecular polarity, and how force interactions occur at the molecular level. It is intended for students who already have functional knowledge of basic kinetic molecular theory. Note: Only registered users have access to PhET teacher-contributed resources, but registration is free and easy.

• Physics First Teaching about Heat and Thermal Energy Unit
• Conceptual Physics Teaching about Heat and Thermal Energy Unit
• Algebra-Based Physics Teaching about Heat and Thermal Energy Unit
• AP/Calculus-Based Physics Teaching about Heat and Thermal Energy Unit