• 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/M7b. The idea of atoms explains the conservation of matter: If the number of atoms stays the same no matter how the same atoms are rearranged, then their total mass stays the same.
• 6-8: 4D/M11. Substances react chemically in characteristic ways with other substances to form new substances with different characteristic properties.
• 6-8: 4D/M12. If samples of both the original substances and the final substances involved in a chemical reaction are broken down, they are found to be made up of the same set of elements.
• 6-8: 4D/M13. The idea of atoms explains chemical reactions: When substances interact to form new substances, the atoms that make up the molecules of the original substances combine in new ways.

• 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.

This lesson, a PhET Gold Star winner, provides guidance for beginners who are using the related simulation Balancing Chemical Equations. It contains pre-lab assessment, student guide, background information and lesson plan, homework problems, and an extension activity. Overall, a fun and game-like method to learn about chemical equations.

• Physical Sciences K-8 Molecular Structures and Bonding Unit
• Physics First Molecular Structures and Bonding Unit