Science Matter & Materials Conceptual 11–13 yrs

Physical vs Chemical Changes

物理变化与化学变化

Description

Distinguish between physical changes (reversible, no new substances formed) and chemical changes (new substances formed, often irreversible), using conservation of mass to understand both types

Mastery Evidence

✓ Classifies given changes as physical or chemical with justification
✓ Explains what conservation of mass means and why mass is conserved in chemical reactions
✓ Names observable signs that a chemical reaction has occurred (colour change, gas produced, temperature change, precipitate)
✓ Explains why dissolving is a physical change but burning is a chemical change

Assessment Prompt

If your child dissolved sugar in tea versus burnt toast in the toaster, could they explain which is a physical change and which is a chemical change — and what test would show that mass is conserved in both cases?