What’s the difference between a fruit and a vegetable? A fruit comes out of the flower on a plant and holds seeds. Apples and oranges, peaches and apricots, and all kinds of berries do this. Veggies come from other parts of the plant, like lettuce and spinach (which are leaves) or carrots and onions (which are roots). But then the watermelon walks in: which one is it? Some say it’s a fruit because it comes from a flower and it has seeds — between 200 and 800 of them. But other say it’s a cousin of the cucumber! Watermelon is 9/10 water by weight, hence its name. It turns out you can eat any part of it, even the rind — they say it tastes good if you pickle it. Now that summer’s here, it’s your big chance to try it!

*Wee ones:* Watermelons are green on the outside. Try to find 4 green things in your room.

*Little kids:* If you’ve spat out 2 seeds from a watermelon, what numbers are the next 3 seeds? *Bonus:* We can’t tell you how many seeds are in your watermelon slice, but if you double that number and add 1, you get 9. How many seeds does it have?

*Big kids:* If you slice a watermelon into 7 circle slabs, then cut each circle into 4 slices, do you have enough slices for 2 dozen people? *Bonus:* If there are between 200 and 800 seeds in that watermelon, how many numbers of seeds are there that would give each of those 28 slices a multiple of 10 seeds?

Answers:

*Wee ones:* Possible items include shirts, socks, live plants, and building toys like Legos.

*Little kids:* 3, 4, 5. *Bonus:* 4 seeds. If you added 1 at the end to get 9, you had 8 before that, and if you doubled to get 8, you must have started with half of that, which is 4.

*Big kids:* Yes! You’ll have 28 slices for 24 people. *Bonus:* There are just 2 ways: 280 seeds, and 560 seeds. You need multiples of 28 that are also multiples of 10.

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.