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How Some Friendships Last — and Others Don't

A TED-Ed lesson on the science of friendship — how friends change the way we see the world, why we often underestimate how much people like us (the 'liking gap'), and why friendships matter so much.

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.