Chemistry · KS3 Y8 · Earth & Atmosphere

The three rock families

The three rock familiesFree6:10Heddy Score 3 of 7, below the standard
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What you need to know

  • Igneous, sedimentary and metamorphic rocks form in different ways.
  • Cooling magma forms igneous rocks with crystals whose size depends on cooling rate.
  • Sediments become sedimentary rock, while heat and pressure change existing rock into metamorphic rock.

In this clip

Runs 6:10, from 3:02 to 9:12 of the full video.

Heddy Score3/7, Below the standard
See the seven stars
  • Trusted source · passed. The creator's own upload, live and playable here.
  • On the map · not judged yet. A teacher watched it: it mainly teaches this map topic.
  • Spec-true · not judged yet. Accurate, and right for the current UK specification.
  • Focused · passed. One idea, short enough to watch in one go.
  • Accessible · passed. Good captions, clear sound and pictures.
  • Safe for children · not judged yet. Right for 11 to 16 year olds, with no sales pitch.
  • Proven · not judged yet. Earned from our students: they learn from it, find it helpful and watch it to the end.
★ passed · ☆ pending · ✕ failed
Our students

Not enough students yet

Our own students' answers. These are what move ★7 Proven.
On YouTube

1.59M views · 21.9K likes · CrashCourse 17.3M subscribers

As reported by YouTube on 2026-11-02. Not part of the Heddy Score.
How the Heddy Score works

Why we picked it

Uses clear examples to compare the three rock families and then show how they change in the rock cycle.

CrashCourse on YouTubechecked 2026-10-20

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