Physics · KS3 Y8 · Waves (Light & Sound)
Light travels in straight lines
Light travels in straight linesFree1:55Heddy Score 3 of 7, below the standard
What you need to know
- The ray model treats light as travelling in straight lines called rays.
- When light reflects, the angle of reflection equals the angle of incidence (the law of reflection).
- Some light reflects at a water surface and some passes in.
- Light changes direction when it passes from air into water; this is refraction, and it makes a straw look bent.
In this clip
Runs 1:55, from 0:50 to 2:45 of the full video.
Heddy ScoreSeven checks every clip must pass before students see it: trusted, on the map, accurate, focused, accessible, safe, and proven by students.3/7, 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.
Our students
Not enough students yet
Our own students' answers. These are what move ★7 Proven.On YouTube
How the Heddy Score works1.07M views · 15.3K likes · CrashCourse 17.3M subscribers
As reported by YouTube on 2026-11-02. Not part of the Heddy Score.Why we picked it
The opening of this episode gives a clean, well-animated introduction to rays, the law of reflection and refraction.
CrashCourse on YouTubechecked 2026-10-22
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