Digging Way, Way Deep

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.

Digging Way, Way Deep

August 29, 2014

Have you ever driven through a long tunnel? Is that the coolest thing or what? It’s pretty exciting to know you’re driving straight through an enormous mountain or under a roaring river. And in fact it takes hard work to build these roads. There are 3 basic ways to make a tunnel. One is “cut and cover,” which means to dig through a mountain of dirt, then cover your new tunnel with the dirt you dug out. The second way is “boring,” which doesn’t mean it’s dull: it means drilling through solid rock, leaving the mountain above you in place. The final is to “immerse,” or sink tubes underwater down to the riverbed (floor). The longest tunnel you can drive is the 15-mile Laerdal Tunnel in Norway. It’s so long that construction workers left some caves in place so drivers can at least see cool rock formations. And the longest water tunnel is the Delaware Aqueduct, an 85-mile tunnel that brings 600 million gallons of water to New York City every year…that would be one long boat ride!

Wee ones: If you drive through a 2-mile tunnel, then drive back through it the other way, how many miles did you drive inside the tunnel?

Little kids: Which is longer, the 15-mile Laerdal Tunnel or the 85-mile Delaware Aqueduct?  Bonus: How much longer is the longer one?

Big kids: In the Laerdal Tunnel there’s a cave about every 3 1/2 miles along the way. If the first is 3 1/2 miles into the tunnel, how many cave spots are there in total?  Bonus: If it takes you 20 minutes to drive that tunnel, what’s your speed in miles per hour? (Reminder: An hour has 60 minutes.)




Wee ones: 4 miles.

Little kids: The Delaware Aqueduct.  Bonus: 70 miles longer.

Big kids: 4 spots, at 3 1/2, 7, 10 1/2, and 14 miles. The next would be past the 15-mile mark.  Bonus: 45 miles per hour. You can drive 15 miles in 1/3 of an hour, so you can drive 3 times that distance in a full hour.

And if you missed it yesterday, Bedtime Math has a new video on Science Friday. See how waffles and math add up when you play with your food!

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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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