Biology · KS3 Y8 · Human Body Systems
The circulatory system
b27Free4:42Heddy Score 2 of 7, below the standardPlays from youtube-nocookie.com. No YouTube cookies until you press play.
What you need to know
- Fish have a single circulation while humans have a double one
- The heart has four chambers and valves stop blood flowing backwards
- A group of cells in the right atrium acts as a natural pacemaker
In this clip
0:27–4:42The heart and double circulationgcse-biol-4-2-2-2aHeddy ScoreSeven checks every clip must pass before students see it: trusted, on the map, accurate, focused, accessible, safe, and proven by students.2/7, Below the standard
- 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 · not judged yet. 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
How the Heddy Score worksNot enough students yet
Our own students' answers. These are what move ★7 Proven.Why we picked it
A short GCSE lesson on the heart and double circulation, including pacemakers.
Freesciencelessons on YouTubechecked 2026-10-16