Everyone knows the Slinky. Beloved by children and physics teachers, this toy debuted in 1945 and hasn’t slinked away since. Odds are good that every kid had at least one Slinky during their lifetime and if they didn’t actually own one, they’ve certainly played with somebody else’s.

How did a simple metal coil become such a childhood icon? Naval engineer Richard James was testing tension springs for his suspension system when one of the springs ran away from him. Or rather, it fell and then walked away, admittedly strange behavior for an inanimate object. James brought the novelty home to his family and we have his wife to thank for the name Slinky. A few modifications later, James unleashed the Slinky on an unsuspecting public who snatched up every last one of them just in time for Christmas.

The instructions were simple: place the Slinky at the top of the stairs or at an incline, give it a little push and watch it slink down down down. Two Slinkies were better than one because you could race them. The simple coil was even eye pleasing in a minimalist sculpture sort of way and if you held a Slinky end in each hand, you could pretend you were playing the accordion. Yep, Slinkies were fun but they really hit their apex in the 1960s when the legendary commercial embedded the Slinky jingle in pop culture. Don’t start humming the song because it is addictive.

Whether you use a Slinky to demonstrate scientific principals or have half a dozen of them racing down your stairs right now, you can’t deny the attraction of this toy for every new generation. New versions of the toy include Slinky Junior, Plastic Slinky (in fun colors!) and Slinky Pets; anything can be Slinkified by attaching it to a spring coil. And yet, the original Slinky has remained unchanged after 50 years on the market, a true and enduring classic.

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