A red hot steel I-beam is molded at the factory, moving back and forth within the machines as it takes shape in the form of the letter I. This classic Sesame Street clip was first seen in 1980 during the show’s 12th season.

Next: More Sesame Street clips, including Shape Organization, Geometry of Circles, Old Paper, New Paper, Numerosity and Loaf of Bread, Container of Milk, Stick of Butter.

Bonus from the National Film Board of Canada: How Do They Recycle Steel?

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