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Wonderopolis

What Is a Spit Valve?

We don’t mean to toot our own horn, but we think today’s Wonder of the Day will be music to your ears.

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What Is a Spit Valve?
Who Is Uncle Sam?

Today’s Wonder of the Day features everyone’s favorite uncle!

#527

Who Is Uncle Sam?
How Do Mood Rings Work?

We hope you’re in the mood for an interesting Wonder of the Day today!

#412

How Do Mood Rings Work?