Yes, You’re Made of Water

Yes, You’re Made of Water

May 14, 2019

As you know, you have all kinds of weird, goopy things inside your body. You have a heart, a stomach and a brain, and little tubes called arteries and veins that carry blood. What’s crazy is what each of these parts weighs. More than half your weight is just plain old water. When you were born, it was closer to 3/4 of your total weight! We just don’t notice, since all that water is mixed into our blood, skin, and other body parts. Speaking of which, your skin is your biggest organ. A grown-up’s skin by itself weighs about 20 pounds! Meanwhile, bones take up about 1/7th of your weight. But water still wins. Next time you drink some water, think of it as putting more of you back inside you.

Wee ones: Half your weight is water. Find something in the room about half as big as you.

Little kids: If you’re carrying 5 pounds of bone and 6 pounds of skin, how much would you weigh if you were just “skin and bones”?  Bonus: How much more than your bones does your skin weigh?

Big kids: Find out your weight in pounds. If you stand on a scale and drink 2 pounds of water (4 cups), now how much do you weigh?  Bonus: If you weigh 70 pounds, and exactly half of you is water and 1/7 is bones, how much of your weight is other stuff?











Wee ones: Items might include a big stuffed animal, a giant pillow, or a bean bag chair.

Little kids: 11 pounds.  Bonus: 1 pound more.

Big kids: Different for everyone…add 2 to your weight in pounds.  Bonus: 25 pounds, since you have 35 pounds of water and 10 pounds of bone.

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About the Author

Laura Overdeck

Laura Overdeck

Laura Bilodeau Overdeck is founder and president of Bedtime Math Foundation. Her goal is to make math as playful for kids as it was for her when she was a child. Her mom had Laura baking before she could walk, and her dad had her using power tools at a very unsafe age, measuring lengths, widths and angles in the process. Armed with this early love of numbers, Laura went on to get a BA in astrophysics from Princeton University, and an MBA from the Wharton School of Business; she continues to star-gaze today. Laura’s other interests include her three lively children, chocolate, extreme vehicles, and Lego Mindstorms.

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