# 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.)