# Sleeping and Swimming – at the Same Time!

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.

# Sleeping and Swimming – at the Same Time!

July 6, 2017

If only we humans could sleep as well as animals. They somehow manage to catch z’s even when they’re on the move. For water animals who need to breathe air, they have no choice: they can’t just sink to the ocean floor while napping! So dolphins let 1/2 of the brain sleep while the other half is awake, with one eye open. While the left half sleeps, the right eye is shut, then vice versa. Seals also sleep this way, leaving one flipper ready to flap around. Air-breathing water animals need to solve other kinds of problems – like otters, who tie their tails around seaweed to keep from floating away while they nap. And albatrosses can actually sleep while flying! You really have to wonder what kinds of dreams these animals have.

Wee ones: Close your 2 eyes. Now open both. Now see if you can wink: try to close just 1 eye!

Little kids: If 3 seals and 3 dolphins are napping, each with 1 eye open, how many eyes are closed?  Bonus: If there are 10 dolphins and 1/2 of them are sleeping with 1 eye open and the rest are wide awake, how many open eyes do they have altogether?

Big kids: Sloths, the laziest animals out there, sleep as much as 20 hours in one day. If you sleep just 10 hours a night, how much more than you does a sloth sleep in a week?  Bonus: If an albatross flies for 2 hours and sleeps 1/5 of the time, how many minutes of sleep does it get? (Reminder: An hour has 60 minutes.)

The sky’s the limit: Suppose a bunch of dolphins are trying to nap, and those who are succeeding each have 1 eye open. If there are the same number of awake dolphins as sleeping dolphins, and there are 40 more open eyes than closed ones, how many dolphins are there in total, and how many are asleep vs. awake?