The post The Speediest Snail appeared first on Bedtime Math.

]]>Sometimes even snails like to show off their speed. Every summer those sorts of snails come together at the World Snail Racing Championship in Congham, England. The snails start in the middle of a table, and have to slime their way to a circle 13 inches out, just a little longer than a grown-up’s shoe. As we see in the video on this page, they don’t move fast, but someone has to win in the end. Still, no snail has beaten the world record of 2 minutes, set by Archie back in 1995. But since most snails can move only 3 inches per minute, these speeder snails leave the rest in the dust.

*Wee ones:* Who’s faster, a snail who finishes the race in 4 minutes, or one who finishes in 3 minutes?

*Little kids:* If one snail takes 5 hours to cross the street and another takes 9 hours, how much longer does the slower snail take? *Bonus:* If another snail’s time is halfway between those, how many hours does that 3rd snail take?

*Big kids:* Most snails move only 3 inches a minute. About how long would it take a regular snail to crawl those 13 inches? *Bonus:* In what year will Archie’s 1995 record have stood for 25 years?

Answers:

*Wee ones:* The snail who takes 3 minutes, because that’s the smaller amount of time.

*Little kids:* 4 more hours. *Bonus:* 7 hours.

*Big kids:* About 4 minutes (actually 4 1/3 minutes, or 4 minutes 20 seconds). *Bonus:* In the year 2020.

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]]>The post Walking on the Moon appeared first on Bedtime Math.

]]>Wow — on this very day 48 years ago, men walked on the moon for the first time. Before that day, no human had never stood anywhere in the universe except on our own planet Earth. Since our moon is about 240,000 miles away, it took the astronauts 4 days to fly there in the Apollo 11. The rocket’s computer system was simpler than today’s phones or even some of your toys! Once the astronauts stepped out of the lunar lander, they walked around for 2 1/2 hours. They collected moon rocks and planted an American flag. They also did giant 2-footed kangaroo jumps, thanks to the Moon’s weak gravity. Check out more moon math below!

*Wee ones: *Look out the window. Do you see the Moon in the sky? If yes, what shape is it?

*Little kids: *If it took 4 days to fly one way to the moon and the same time back, how many days did the astronauts fly in total? *Bonus:* Was the person reading this bedtime math problem to you already born when the astronauts landed 48 years ago? Find out his/her age!

*Big kids:* In what year did this famous journey happen, if it was 48 years ago today? *Bonus:* If the Apollo flew exactly 240,000 miles in those 4 days, how many miles per day did it fly?

*The sky’s the limit — for real:* If the rocket that brought the Apollo had flown twice as far the 1st day as the 2nd day, which was twice as far as the distance flown on the 3rd day, which was twice as far as the 4th day, how much of the 240,000 miles did it fly on the 1st day?

Answers:

*Wee ones:* Look for our shiny Moon…If you don’t see it, you can check on other nights until it’s up on a clear night! You’ll also see that the lit part changes shape.

*Little kids:* 8 days of flying. *Bonus:* Different for everyone…see if that person has lived more or fewer than 48 years!

*Big kids:* In 1969. *Bonus:* 60,000 miles each day.

*The sky’s the limit:* 128,000 miles. With those ratios of distances, on the 1st 3 days Apollo flew 8 times the final day distance, then 4 times that distance, then 2 times that distance, respectively. So the whole trip distance was 15 times the final day’s trip. That gives us 16,000 miles on the final day. Then you just multiply by 2, 4 and 8 to get 32,000 for the 3rd day, 64,000 the 2nd day and 128,000 the 1st day. To double-check, those four numbers do add up to 240,000!

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]]>The post How Teeny Is a Baby Bunny? appeared first on Bedtime Math.

]]>Have you ever seen a real baby bunny, just a day or two old? They don’t look anything like what you’d expect. Photographer Arefin Ashraful’s pet rabbit, Tooni, had 4 baby bunnies, called “kittens” just like baby cats. Arefin took amazing pictures of them right from day 1 to show how baby bunnies grow. They don’t have any fur for the first 7 days, and their eyes don’t open until day 10! (That’s one of the cutest pictures, shown here). As you can see from Arefin’s hand, the kittens are only a couple of inches long at birth. But they grow really fast: by 10 months they’re full-size like their parents. We humans take a good 14-18 years to do that!

*Wee ones:* Find 4 things small enough to fit in your hand like this baby bunny.

*Little kids:* If Tooni had 4 baby bunnies, how many bunnies did Arefin then have all together? *Bonus: *If the bunnies open their eyes on day 10, how many days do they spend with them closed?

*Big kids:* If the bunnies were born on a Tuesday, on what day of the week would their eyes open if it’s their 10th day of life? *Bonus:* If Tooni’s 4 kittens have 7 kittens each, and another bunny Toby’s 5 kittens have 5 kittens each, which bunny has more “grandkittens”?

Answers:

*Wee ones:* Items might include bouncy balls, marbles, Lego pieces, a bar of soap, or keys.

*Little kids:* 5 bunnies. *Bonus: *9 days.

*Big kids:* On Thursday of the next week…their 10th day of life is 9 days later. *Bonus:* Tooni. She has 4 x 7 = 28 grandkittens, while Toby has 5 x 5 = just 25 grandkittens.

And thank you Arefin for sharing your incredible photos with us!

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]]>The post Daredevil Skater Boy appeared first on Bedtime Math.

]]>If you ever rollerskate or rollerblade, you know how much fun it is to strap wheels to your feet. It’s like turning each foot into a car. But you probably haven’t tried to skate UNDER a car, much less 39 of them! A boy in Bangalore named Gagan Satish became famous because he can skate with his legs sticking straight out to the sides. He holds his ankles in his hands, and his face whizzes by just 5 inches above the ground! So he can scoot right under a parked car, and holds a record for zooming under a line-up of 39 of them. From these photos it doesn’t look comfortable, but it works for Gagan.

*Wee ones:* A roller skate wheel looks like a circle from the side. Try to find 4 circles in your room.

*Little kids:* If your roller skate has 2 wheels under your toe and 2 wheels under your heel, how many wheels does your foot have in total? *Bonus:* If you then skate like Gagan under 3 cars, how many wheels do those cars have? Count up by 4s if you can!

*Big kids:* If Gagan took exactly 2 seconds to pass under each car, how long would it take to skate under the row of 39 cars? *Bonus:* If he wanted to skate under 100 cars, how many more cars would he need in the lineup?

*The sky’s the limit:* If in the 39 car lineup, every 3rd car starting with the 3rd has the engine running, every 4th car starting with the 4th is really muddy, and every 5th car starting with the 5th is 2 inches lower than the rest, how many cars don’t give Gagan any extra trouble?

Answers:

*Wee ones:* Items might include balls, buttons, the rim of a cup or plate, or the colored part of your eye (the iris)!

*Little kids:* 4 wheels. *Bonus:* 12 wheels.

*Big kids:* 78 seconds (1 minute 18 seconds). *Bonus:* 61 more cars.

*The sky’s the limit:* 16 cars offer no extra trouble. From 1 to 39 there are 13 multiples of 3, 9 multiples of 4, and 7 multiples of 5, or 29 cars. But there are some overlaps among those sets:

– 3 of the 4-multiples overlap with the 3-multiples (12, 24 and 36)

– 1 of the 4-multiples overlaps with the 5-multiples (20)

– 2 of the 5-multiples overlap with the 3-multiples (15 and 30)

So we have to subtract those 6 overlaps from the 29 cars to avoid double-counting, giving us just 23 troublesome cars. That leaves 16 cars with no issues. If you’d like to say which ones they are, they are cars #1, 2, 7, 11, 13, 14, 17, 19, 22, 23, 26, 29, 31, 34, 37, and 38.

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]]>The post Banging out That Song appeared first on Bedtime Math.

]]>Usually you aren’t supposed to pound on your toys with hammers. But there’s one toy where you can do that all you want: the xylophone. This musical instrument has wooden bars of different lengths that you hit with “mallets” (hammer-like sticks) to play notes. If the bars are metal, it’s called a “glockenspiel” and the notes sound like bells. This photo shows the Lancaster Percussion Ensemble playing GIANT xylophones the size of pianos — some need 2 people playing them! And this video shows a musician playing the super speedy “Flight of the Bumblebee.” That’s some fast hammering!

*Wee ones:* If you play 5 notes on your xylophone, what numbers do you say to count them?

*Little kids:* If you and 3 friends play a giant xylophone together and each one of you has 2 mallets, how many mallets do you all have? *Bonus:* If on your xylophone you play the notes C, E, G, then C again, E again and so on, what’s the 8th note you play?

*Big kids:* Xylophones are laid out like a piano keyboard. If each one has 3 whole “octaves” of notes, where each octave has 7 white keys and 5 black keys, how many keys can 1 xylophone have? *Bonus:* If you play all the white keys twice and your friend plays all the black keys 3 times through, who finishes first? (Assume you play your notes on the same beat.)

Answers:

*Wee ones:* 1, 2, 3, 4, 5!

*Little kids:* 8 mallets total, since there are 4 people (remember to count yourself!). *Bonus:* E.

*Big kids:* 36 keys (3 sets of 12). *Bonus:* You finish first. You have to play 21 notes twice (42 in total), while your friend has to play 15 notes 3 times (45 in total).

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]]>The post A Whale of a Waterslide appeared first on Bedtime Math.

]]>The waterslide is one of the most exciting summer treats: fast turns, jets of water shooting at you, giant splash at the bottom. Now imagine if the whole waterslide were alive! Scientists actually caught photos of a dolphin taking waterslide rides down the back of a whale. We hope the whale didn’t mind: humpback whales weigh almost 80,000 pounds, while a bottlenose dolphin weighs less than 1/100th of that. Never mind that those whales grow to 50 feet or longer…these dolphins reach only 10-12 feet at most. It all worked out, giving that playful dolphin one more reason to smile.

*Wee ones:* One dolphin took 6 rides in a row. Flap your arms like flippers, and hop 6 times!

*Little kids:* If the dolphin slides down the right side of the whale, then the left side, then the right side again to repeat…after 5 turns, how many times does it slide to the right? *Bonus:* If it takes the dolphin 10 seconds to get on top of the whale and then 4 seconds to slide down, how long does each ride take?

*Big kids:* If the 12-foot dolphin is a whole 39 feet shorter than the whale, how long is the whale? *Bonus:* If a 79,000-pound whale weighs exactly 100 times the dolphin, how much does the dolphin weigh? (*Hint if needed:* To start, what if it weighed 10 times as much?)

*The sky’s the limit:* Back to that sliding game…if the dolphin slides down the right side, then the left side, then the left again, then repeats, which side will it pick for the 123rd turn?

Answers:

*Wee ones:* Count your hops: 1, 2, 3, 4, 5, 6.

*Little kids:* 3 times to the right (turns 1, 3 and 5). *Bonus:* 14 seconds.

*Big kids:* 51 feet. *Bonus:* 790 pounds, a bit more than your usual dolphin.

*The sky’s the limit:* The left side. 123 is a multiple of 3, and all multiples of 3 will be the same. You can tell whether any number is divisible by 3 by adding up its digits: if they add up to a multiple of 3, then so is the number. In this case, the digits add up to 1+2+3=6!

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]]>The post Worms for Dinner appeared first on Bedtime Math.

]]>When we say someone “eats like a bird,” that should mean the person eats a LOT. Every day birds have to eat many times their weight in food so they have energy to fly. But hopefully eating like a bird doesn’t mean eating *what* a bird eats. Some birds eat tasty people-food like berries and fish. But a few feathery friends — the robin, the woodcock, and the warbler — all like worms. As the birds walk around, their stomping shakes up the earthworms underground and makes them move around, making it easy for the birds to find them. Girl robins eat more worms than boy robins, and warblers like fuzzy caterpillars even better. Yum!

*Wee ones:* If a bird eats a worm, then a caterpillar, then a worm, then a caterpillar…what do you think the bird eats next?

*Little kids:* If 3 birds go hunting for worms, how many stomping feet do they have? *Bonus:* In this video, the very hungry bird catches a worm only some of the times that it pecks the ground. If the bird pecks 10 times but grabs a worm only 3 of those times, how many pecks were misses?

*Big kids:* If a robin slurps up 6 worms every 10 minutes, how many can it eat in 20 minutes? *Bonus:* If the robin keeps eating 6 worms every 10 minutes, how many can it eat in 1 hour? (*Reminder:* An hour has 60 minutes.)

Answers:

*Wee ones:* A worm!

*Little kids:* 6 feet. *Bonus:* 7 pecks.

*Big kids:* 12 worms. *Bonus:* 36 worms, since there are 6 sets of 10 minutes.

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]]>The post When Surfers Can’t Wait Their Turn appeared first on Bedtime Math.

]]>One really fun summer sport is surfing. You walk out into the ocean, stand on a long skinny surfboard, and try to ride it as the waves push you along. It’s very hard not to fall off — so imagine riding it with dozens of other people! These 66 people in California squeezed onto a 42-foot-long surfboard and rode it for a whole 15 seconds, beating the world record for the most surfers on the biggest surfboard. The board weighed 1,300 pounds, but of course had to carry 10,000 pounds of people. We hope once everyone fell off that somebody remembered to grab the surfboard.

*Wee ones:* If you surf the 1st wave, then skip the 2nd, then ride the 3rd, then skip the 4th, what do you do on the 5th wave?

*Little kids:* The surfboard was 11 feet wide, maybe almost as wide as your room! Lie down head to toe with a grown-up, and guess whether the 2 of you could stretch across that board. If you lay across it, by how many feet would you fall short of stretching across? *Bonus:* Once the 1st surfer fell off, how many of the 66 surfers were still hanging on?

*Big kids:* If the surfers weighed 10,100 pounds and the board weighed 1,300 pounds, how much did that weigh all together? (*Hint if needed:* Start with the board weighing just 1,000 pounds.) *Bonus:* If your regular surfboard is only 1/6 as long as this monster 42-foot one, how long is your board?

Answers:

*Wee ones:* You ride the 5th wave.

*Little kids:* See if your height in feet + a grown-up’s height add to 11. *Bonus:* 65 surfers.

*Big kids:* 11,400 pounds. *Bonus:* 7 feet long.

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]]>The post How to Fly with a Party Balloon appeared first on Bedtime Math.

]]>The best party balloons are the ones that float. If you don’t hang on, they’ll fly up into the sky. So a crazy guy named Daniel Boria wondered if HE could fly using party balloons. He tied 110 balloons to a folding chair and flew right into the sky — really! He wanted to float over the Calgary Stampede rodeo in Alberta, Canada, and then jump off and parachute down. But the wind blew him the wrong way, and he landed in a field instead. He did all this to let people know about the soaps he sells. Maybe he should stick to ads on the radio.

*Wee ones:* If Daniel blew up red, blue, yellow, green, and white balloons, how many colors is that?

*Little kids:* If Daniel took off at 2:00 pm and crash-landed 2 hours later, when did he land? *Bonus:* If Daniel really needed just 100 balloons, not 110, how many extra balloons did he blow up?

*Big kids:* In the 1980s, a guy nicknamed Lawn Chair Larry tried this trick with 45 GIANT balloons. How many more balloons did Daniel use? *Bonus:* If Daniel spent $1 for every pack of 10 balloons to make 110, plus $20 on the chair, how much did his flying machine cost?

*The sky’s the limit — for real:* If 1/2 of the 110 balloons had popped after 10 minutes, and then 1/5 of the ones *left* had popped 1 minute later, and then 1/2 of the ones left after that had popped, how many balloons would have been left?

Answers:

*Wee ones:* 5 colors.

*Little kids:* At 4:00 pm. *Bonus:* 10 extra balloons.

*Big kids:* 65 more balloons. *Bonus:* $31, since the 110 balloons cost $11.

*The sky’s the limit:* 22 balloons left. If 1/2 the balloons popped, he’d lose 55, leaving him with 55. If 1/5 of those popped he’d lose another 11, leaving him 44. Then if 1/2 of those popped, he’d lose 22 of them and have 22 left.

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]]>The post Rock Star Robot appeared first on Bedtime Math.

]]>People who play the guitar well can make amazing music. Well, here’s a robot that can jam, too. Fastythefastcat built a robot out of Lego Mindstorms pieces that strums the guitar — and plays a real song! As we see in this video, a robot arm with a tooth-shaped tip drags across the strings; at the other end, 6 Lego pieces take turns pushing down the strings in the right spots to play different sets of notes, called “chords.” Next thing we know, the robot’s going to ask for a trumpet.

*Wee ones:* What numbers would you say to count the 6 strings on that guitar?

*Little kids:* If the robot needs 6 “fingers” to press on the strings and 1 more finger to play them, how many fingers touch the strings? *Bonus:* In the verses the robot plays just 3 chords (sets of musical notes): A minor, F, C, then it returns to A minor to repeat. Which chord is the 8th chord it plays?

*Big kids:* If the robot uses 8 gears and twice as many beams (stick pieces), how many total pieces is that? *Bonus:* If the robot repeated this 4-chord set the whole time — A minor, F, C, G — which chord would be the 80th one played?

Answers:

*Wee ones:* 1, 2, 3, 4, 5, 6.

*Little kids:* 7 “fingers.” *Bonus:* F.

*Big kids:* 24 pieces, since it uses 16 beams. *Bonus:* G, since 80 is a multiple of 4 and G lands on all the multiples of 4.

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