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 | Not yet | Approaching | Mastered |
|---|---|---|---|
| Physical vs. chemical change | Calls every change the same kind — all physical or all chemical. | Defines each kind but cannot sort real examples. | Sorts changes as physical or chemical and gives the reason for each call. |
| Signs of a chemical change | Cannot name a clue that a new substance formed. | Names one sign but overlooks the others. | Looks for a color change, gas, temperature change, or a new solid and uses them as evidence a new substance formed. |
| Conservation of mass | Thinks matter disappears when something burns or dissolves. | States that mass is conserved but cannot show it. | Predicts and measures that the total mass stays the same before and after a change. |
| 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) | Treats the science as isolated facts; makes no cross-domain connection. | Names a link to history, reading, or writing but cannot defend why it matters. | Connects the unit to its anchor across History · Reading · Writing (plus chosen electives) and defends why the connection matters. |
“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.