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In Harry Potter and the Order of the Phoenix, Fred and George Weasley invent Extendable Ears in order to overhear important conversations among the adults of the novel. For those who are fans of the series, you will know that this device is one of many of the Weasley twins’ inventions, and you will also recall that Harry hears significant information via the Extendable Ears while visiting Arthur Weasley in St. Mungo’s Hospital.

The Extendable Ears are a magical device: two ear-shaped listening pieces attached with a magic-infused string that directs one end of the device toward closed doors or down the stairs of the Order’s headquarters at Grimmauld Place.

Our question: How would we, as Muggles (non-wizard folk, in the parlance of the series), make a similar device?

Solution? The tin can phone, beloved childhood science classic. Two tin cans, a nail and hammer, and kitchen twine. We can hear each other because our voice causes the air to vibrate, and these vibrations travel along the twine. Simple, elegant, very cool. A little bit of science to connect to our current literature… What is the science behind the magic? We must always ask ourselves this question, yes?

To make the phones:

The kiddos used Sharpies to decorate the tin soup cans. I let Eric do this, too, guiding his hand just a bit to keep the Sharpie aimed at the can. I did end up with red Sharpie on my temple and my left shoulder nonetheless.

After this step, we made holes in the bottom of the can with a hammer and nail.

Oh, I forgot to mention that, prior to turning the kiddos loose with the cans, I used duct tape to cover over the open edge and any sharp parts that might exist. We don’t want boo-boos around here!

We threaded some twine through both holes, tied knots, and ta-da! A tin can phone!

Katie hangs out in the chair while I am at the other end. I think tomorrow we might try a longer piece of twine and see how far apart we can be outdoors.

Eric’s turn!

This turned out to be easy, free (we had all supplies on-hand), and relevant, with a big playtime pay-off. Fun!