Orange You Glad You’re Not Round?

Here's your nightly math! Just 5 quick minutes of number fun for kids and parents at home. Read a cool fun fact, followed by math riddles at different levels so everyone can jump in. Your kids will love you for it.

Orange You Glad You’re Not Round?

April 7, 2016

It’s funny how almost all fruits are round. Apples, oranges, watermelons, kiwis…why is that? Mother Nature may have a few reasons, one being that the fruit can roll away once it falls from the tree, and spread seeds for new trees. But that all goes out the window with these 5-sided oranges from Japan. What the heck is Nature doing here? Don’t worry — the oranges don’t grow on the tree like that by themselves: the farmer puts a wooden frame around each one as it hangs from the branch. As the orange grows, it squishes itself into the corners and takes that 5-sided shape. The Japanese have used this idea to grow cube-shaped watermelons and other funny-shaped fruit. Best of all, these oranges won’t roll off the table before you get to eat them.

Wee ones: Which has more sides, a square watermelon slice or a 5-sided orange slice?

Little kids: What do you call a shape with 5 straight sides, like we see here?  Bonus: It took the fruit growers 3 years to make this idea work. If they got it working in 2014, when did they start?

Big kids: By making cube-shaped watermelon, the Japanese can fit more pounds of watermelon on a shelf. If you have 4 rows of 6 cube watermelons, how many melons do you have?  Bonus: If you have 20 5-sided oranges side by side in a ring, so each one is touching the 2 it sits between, how many faces (flat sides) aren’t touching anything?

The sky’s the limit: If you stack a cube of 5 watermelons across, 5 front to back and 5 tall, how many watermelons are hidden inside, with no faces facing the air or the floor?




Wee ones: The 5-sided orange slice.

Little kids: A pentagon.  Bonus: In 2011.

Big kids: 24 melons.  Bonus: 60, since each orange has 3 free faces.

The sky’s the limit: 27, since that inner cube will be 3 watermelons across, 3 deep and 3 tall!

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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 while still in diapers, 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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