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 then what about these 5-sided oranges from Japan? 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. Japanese farmers use this same trick to grow cube-shaped watermelons and other funny-shaped fruit…and none of it will roll off your plate.
Wee ones: Which has more sides, a square watermelon slice (4 sides) or this orange slice (5 sides)?
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 orange slices side by side to make a full circle, so each one is touching the 2 it sits between, how many orange edges 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 edges.
The sky’s the limit: 27, since that inner cube will be 3 watermelons across, 3 deep and 3 tall!
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.