Unit 03 · Chemical & Physical Changes
Some changes rearrange matter without making anything new — melting ice, tearing paper, dissolving sugar. Those are physical changes. A chemical change makes a brand-new substance, and it leaves clues: a color shift, bubbles of gas, a jump in temperature, or a new solid. Through every one of these changes the total mass stays the same — nothing is truly created or destroyed. Mastery means you can tell the two kinds of change apart and back your call with evidence you can point to.
| Criterion | Developing | Proficient | Mastery |
|---|---|---|---|
| Physical vs. chemical change | Calls every change the same kind — all physical or all chemical. | Defines each kind but cannot sort real examples. | Classifies changes by whether substance identity changes, explaining physical examples such as melting, tearing, and dissolving sugar. |
| Signs of a chemical change | Cannot name a clue that a new substance formed. | Names one sign but overlooks the others. | Uses observations and property checks as evidence of a new substance; a color change or bubbles alone are not proof. |
| Conservation of mass | Thinks matter disappears when something burns or dissolves. | States that mass is conserved but cannot show it. | Predicts and checks mass conservation within measurement uncertainty, accounting for gas that enters or leaves the measured system. |
| Evidence & explanation | Guesses without pointing to what was observed. | Describes what happened but cannot tie it to a new substance. | Uses careful observations to argue whether a new substance formed. |
| Lab technique (change investigation) | Mixes samples with no plan and no measurement. | Runs the change but records observations loosely. | Runs a controlled change, measures mass before and after, and records every clue carefully. |
| Integration (cross-domain) | Makes no supported connection between the source and the science. | Uses the source but needs help connecting evidence, writing, or limitations to the science. | Independently connects History, Reading, and Writing using a cited source, appropriate evidence, a limitation, and a scientific explanation. |
Integration is reported separately and cannot lower the science grade or block a science demonstration pass. Science and practical criteria determine that pass. Use the integration guide's evidence checklist for the separately reported criterion.
“When I mixed the baking soda and vinegar it fizzed and turned cold — gas and a temperature change — so a new substance formed. That’s a chemical change. I weighed the sealed bag before and after and the mass matched, because the gas stayed trapped inside.”
“It bubbled, so something happened. It felt lighter after, so maybe some mass disappeared? I think it’s a chemical change but I’m not sure why.”
You demonstrate this unit through a hands-on change investigation — running a physical change and a chemical change, weighing before and after, and reading the evidence aloud — not a multiple-choice test. A criterion counts as mastered only when you can both produce the change and explain what the clues tell you. Mastery is demonstrated, not awarded.
A 5-page clipboard packet — unit overview, key terms, the mastery rubric, anchor examples, and a score sheet you can print and grade against.