"The Renaissance was a time of great creativity and invention," says Carmine. "Artists and scientists wanted to investigate the real world, rather than just the spiritual world, which had been all-important during the Middle Ages.

"Like many people, Leonardo was fascinated by the idea of flying—so he put his brilliant mind to work studying how real birds fly. He recorded his observations—and his ideas for flying machines—in his sketchbooks.

"Let's see what we've got here. Do any of these look like they're not Leonardo's inventions? Click on your choice!"

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