物理变化与化学变化
Physical vs Chemical Changes
区分物理变化（可逆，不生成新物质）和化学变化（生成新物质，通常不可逆），并运用质量守恒定律理解这两类变化。
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
学习证据 / Evidence
- 能将给定的变化分为物理变化或化学变化，并说明理由
- 能解释质量守恒的含义，以及为什么化学反应中质量守恒
- 能说出化学反应发生的可观察迹象（颜色变化、产生气体、温度变化、生成沉淀）
- 能解释为什么溶解是物理变化，而燃烧是化学变化
- 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
评估问题 / Assessment
如果{{name}}把糖溶解在茶里，又把面包片放进烤面包机里烤焦了，能否解释哪一个属于物理变化、哪一个属于化学变化？并且用什么检验可以说明两种情况下质量都守恒？
If {{name}} 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?