Science
Matter & Materials
Conceptual
11–13 yrs
Pure Substances & Mixtures
纯净物与混合物
Description
Distinguish between pure substances and mixtures, identify formulations as useful mixtures with precise compositions, and use melting and boiling points to test for purity
Mastery Evidence
- Explains why a pure substance has a sharp, fixed melting point but a mixture melts over a range
- Identifies common formulations (medicines, alloys, paints, fuels) as deliberate mixtures
- Explains what impurities do to melting and boiling points
- Distinguishes mixtures from compounds at the particle level
Assessment Prompt
If your child was checking whether a sample of water was pure, could they explain one test they could do — and say what result would tell them it was definitely pure versus a mixture?
