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Why Series

2 lessons available.

EP24 · 2026-08-10

How QR Codes Work

A QR code may look like a random grid, but every region has a job. This episode follows a scan from the camera image to position detection, data decoding, error correction, and the final action on your phone.

Intermediate6 min

EP23 · 2026-08-10

Why Series: Why Do Airplanes Leave White Lines in the Sky?

Those white lines behind airplanes are contrails: narrow clouds of ice crystals. This episode follows their formation from hot jet exhaust to freezing upper air, explains why some vanish and others spread, and looks at what they can tell us about the atmosphere.

Intermediate5 min