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How Long Can Human Hair Grow?
A TED-Ed lesson starting with a record-breaking 5-meter head of hair. Discover how hair grows from follicles, how keratin hardens each strand, and how special cells decide what kind of hair grows where on your body.
How it works
- Press play to start the video.
- Videos 5 minutes or longer pause once or twice for a quick check. Get it right and you're on your way. If not, you'll see a friendly explanation and the video simply keeps going. Short videos skip the checks.
- At the end there's a 3-question test. Score 60% or more to complete the lesson, and 80% or more to master it. You can always watch again and try for a higher score.