Physical and Chemical Changes
▶︎ Watch it animatedinteractive step-through · ~3 min · optionalA chemical change produces new substances (different composition); a physical change alters form or state but keeps the same substance. Melting, boiling, and dissolving are physical — the molecules survive. The decisive question is always whether the identity of the substance changed.
The misconceptions all judge by surface drama instead of composition: treating bubbles, color changes, or vigorous effects as proof of a chemical change, or thinking boiling and dissolving are chemical. Ask whether new substances formed; if not, it is physical.
The work
3 ways in · any order
Lesson
Physical vs Chemical Change
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A chemical change makes new substances; a physical change does not, whatever the drama. The lesson classifies changes by composition, not appearance, then closes with a ten-scenario check.
Diagnostic
10-item topic check
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Ten items spanning the Topic 4.4 misconceptions: bubbles or drama read as chemical change, boiling called chemical, and dissolving imagined to destroy or chemically alter the substance.
Targeted Practice
Drill a single misconception
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Pick one of the failure modes you missed and drill it on its own. The round is adaptive: two correct in a row clears the misconception and moves you to the next.