This video and lesson is a couple of years old, but is new to me. Here’s how TED-Ed describes it:

Invented in 1793, the cotton gin changed history for good and bad. By allowing one field hand to do the work of 10, it powered a new industry that brought wealth and power to the American South — but, tragically, it also multiplied and prolonged the use of slave labor. Kenneth C. Davis lauds innovation, while warning us of unintended consequences.

I’m adding it to The Best Sites Where Students Can Learn About Inventions.