The post Losing Your Marbles, 13,000 at a Time appeared first on Bedtime Math.

]]>Building marble runs is a blast. It feels great to set up ramps, drop a marble at the top and watch it bounce and roll all the way to the end. Now imagine building a marble run that moves thousands of marbles at a time! Jelle Nikkers, who lives in the Netherlands, put together giant slides, zigzag ramps and tipping seesaws to make a giant machine that moves 11,000 marbles at a time. The marbles roll onto a moving ladder that carries 17 on each rung, then dumps them out at the top onto the ramp. Check out the video to see the marbles do all kinds of tricks, and to hear the rushing river-like sound they make!

*Wee ones:* Which has *fewer* marbles, a seesaw holding 5 marbles or a seesaw holding 7 marbles?

*Little kids:* The first seesaw shown tips when it fills with 10 marbles. If 6 have rolled onto it so far, how many more are needed to tip it? *Bonus:* The machine holds 13,000 marbles total, with 11,000 on the move at once. How many marbles are sitting around waiting their turn?

*Big kids:* The whole marble run is 33 feet long and 4 feet wide! If you and your friends are all 5 feet tall, how many of you have to lie head to toe to stretch longer than the marble run? *Bonus:* If it fits inside a perfect rectangle, how far is it to walk all the way around it?

Answers:

*Wee ones:* The one holding 5 marbles.

*Little kids:* 4 more marbles. *Bonus:* 2,000 marbles.

*Big kids:* 7 of you, since 6 of you will stretch only 30 feet. *Bonus:* 74 feet, since you have to walk the 33 twice and the 4 twice.

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]]>The post The World’s Best Father, Caught on Camera appeared first on Bedtime Math.

]]>Today is Father’s Day, the day we honor our dads for all the great things they do. But dads aren’t always sure that they’re doing a good job. So one dad, Dave Engledow, decided to show the worst possible fathering in a series of pictures. He posed his baby girl Alice with sharp objects, hot ovens, dangerous electrical equipment — and always with Dave’s “World’s Greatest Father” coffee cup in the picture. Now, Alice didn’t REALLY hold marshmallows over a fire or play with toys in the toilet; her dad used the computer to make the photos look that way. But Alice does look like she’s having fun.

*Wee ones:* If Alice is roasting 4 marshmallows, what numbers would you say to count them?

*Little kids:* If the photo shows 5 pancakes in the air, 1 on the hot griddle and 1 on Alice’s spatula, how many pancakes are on their way to Dave? *Bonus:* If there are another 6 pancakes on Dave’s plate, how many are there in total?

*Big kids:* If Dave photographed Alice for 45 minutes in the bathroom, then spent 45 more minutes on the computer to “put” toys in the toilet bowl, how long did that photo take? *Bonus:* If the photo with Alice on the car roof took Dave 240 minutes total, and the computer work took twice as long as the actual picture-taking on the car, for how long did Alice sit on the car?

*The sky’s the limit:* Dad Dave had to snap a lot of pictures, and use up a lot of food. If he took 5 pictures and burned 50 marshmallows total, and used 1 more marshmallow on each photo than the one before, how many marshmallows did he burn on the 4th photo?

Answers:

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

*Little kids:* 7 pancakes. *Bonus:* 13 pancakes.

*Big kids:* 90 minutes. *Bonus:* 80 minutes – you need 1/3 of the total so that the remaining time will be twice as much, or 2/3 (160 minutes).

*The sky’s the limit:* 11 marshmallows. If all 5 pictures used the same number, they’d each use up 10 marshmallows. If we then move a marshmallow from the 2nd photo to the 4th, and 2 marshmallows from the 1st photo to the last, we still use 50 total, but now we’ve used 8, 9, 10, 11, and 12.

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]]>The post One Weird Whale appeared first on Bedtime Math.

]]>When we think of whales, we picture big, round animals moving through the water. But not all whales are shaped like that. The fin whale is long and skinny, almost like an enormous eel. A marine biologist caught this amazing video of a fin whale hauling its 80-ton body out of the water. At 89 feet long it’s the second biggest animal on the planet! Even with that heavy body, fin whales can swim at nearly 30 miles an hour. Because of their speed and color they’re called “the greyhounds of the deep,” because greyhounds are dogs that run super fast (about 40 miles per hour). But a real greyhound might make an easier pet.

*Wee ones:* Fin whales are silvery-grey. Can you find 3 things in your room that are silver or grey?

*Little kids: *If a fin whale does 5 belly flops, what number is the second-to-last flop? * Bonus:* A fin whale can swim 23 miles an hour for a while, but for short bursts it can swim 6 miles an hour faster. What is the fastest it can it swim?

*Big kids:* Eels can be up to 13 feet long. How much longer is that 89-foot whale? *Bonus:* A fin whale weighs 80 tons! How many pounds is that? (*Reminder:* A ton equals 2,000 pounds.)

*The sky’s the limit:* If a whole bunch of kids lie end to end to be as long as that 89-foot whale, how many more 4-foot kids does it take to match the whale than 5-foot kids?

Answers:

*Wee ones:* Items might include socks, shoes, aluminum foil, coins, or other metal objects.

*Little kids:* The 4th belly flop. *Bonus:* 29 miles per hour.

*Big kids:* 76 feet longer. *Bonus:* 160,000 pounds.

*The sky’s the limit:* 5 more kids. It takes 18 5-foot kids to make a chain longer than the whale, because 17 kids would be only 85 feet long. Then it takes 23 4-foot kids to be longer than 89, because 22 kids would be just 88 feet long. So we need 23 kids instead of 18.

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]]>The post Another Flag to Wave appeared first on Bedtime Math.

]]>It’s Flag Day, when the U.S. celebrates its starry, stripy flag of red, white and blue. The thing is, ever since we became a country, we haven’t all celebrated the *same* flag. Remember, America started off with 13 colonies, which became the first 13 United States. So the flag in 1777 had 13 stars in a circle, one star for each state. Then in 1795 we added Vermont and Kentucky, so the stars had to move around to fit 15, this time in rows. Then in 1818 we added 5 more states, bringing the total to 20 — yet another star line-up. Since then the flag has changed more than 20 times. Our current 50-star flag was born in 1960, and is the longest-lasting flag we’ve had!

*Wee ones: *How many points does each little star have?

*Little kids:* Which had more stars, the flag for 15 states or the one for 13 states? *Bonus:* In our flag now, the long rows have 6 stars and the short rows have 5 stars. How much longer are the long rows?

*Big kids:* The 20-star flag had all rows of 5 stars. How many rows of stars must there have been? *Bonus:* The cool circles-of-stars flag here is from 1867, when Nebraska became the 37th state. The outside circle has 11 more stars than the inside circle. How many stars must each one have?

Answers:

*Wee ones: *5 points.

*Little kids:* The flag for 15 states. *Bonus:* 1 star more.

*Big kids:* 4 rows. *Bonus:* 24 stars and 13 stars (for the 13 colonies!). If the outside circle dropped its 11 extras, the total would be 37-11 = 26 split evenly between them, which would be two 13-star circles. Then add 11 back to that outer one to get the 24.

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]]>The post PancakeBot appeared first on Bedtime Math.

]]>What could be yummier than pancakes? Stacks of warm, spongy dough layered with butter and syrup…and now, those pancakes can be shaped like a horse, a cactus or any crazy thing. PancakeBot uses a robot arm to squirt pancake batter in any design you program into it. As we see in this video, the clever bot squirts the outline first, so the batter can cook a bit and hold the rest of the batter when the bot fills in the shape. A 3D printer works this way, too: instead of printing ink on paper, it squirts hot melted plastic in layers to build any shape. If you can’t fit PancakeBot in your kitchen, try squirting batter with a bottle — you might be even better than the bot.

*Wee ones:* If you make 3 dinosaur pancakes and then make a horse pancake to mix things up, how many animal pancakes do you have?

*Little kids:* If you make a horse pancake, a chicken pancake and a fish pancake, how many legs do your pancakes have? (Fins don’t count!) *Bonus:* If you nibble off 1/2 the legs to start, how many pancake legs are left?

*Big kids:* If the machine takes 13 seconds to draw the outline of the pancake and twice as long as that to fill the “wall” with batter, how long does it take to make that cake? *Bonus:* If a pancake cooks for a total of 90 seconds, but the 1st side takes 2 seconds longer than the 2nd side, how long does each side take?

*The sky’s the limit:* If a cactus cake uses 1/2 cup of batter and a horse uses 5/8 cup, and you want to eat 3 cups of batter’s worth, how many pancakes of each shape can you make IF you want at least 1 of each?

Answers:

*Wee ones:* 4 animal pancakes.

*Little kids:* 6 legs. *Bonus:* 3 legs.

*Big kids:* 39 seconds. *Bonus:* 46 seconds and 44 seconds. If the 1st side gave 1 second back to the 2nd side, they’d be even, so they’d each take 45 seconds.

*The sky’s the limit:* 4 horses and a cactus. To use up 3 cups, you’ll need the horses to add up to a round multiple of 1/2, so you can add cacti and reach exactly 3 cups. 4 horses brings you to 20/8 cups, or 2 1/2 cups. That leaves you with room for 1 cactus.

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]]>The post Jenga Cat appeared first on Bedtime Math.

]]>Let’s face it: our pets want to be like us. They want to eat our food, sleep on our beds — and play our games. Some guy trained his cat to play Jenga, where you pull wooden blocks from a stack without making it fall. The cat is pretty good at it, as you can see in this quick video. While her owner loosens the blocks, the cat carefully bats them out of the stack. Then those blocks get placed on top so the game can keep going with a taller and taller tower. How tall can she go without crashing?

*Wee ones:* What shape are those blocks? Can you find 1 shape in your room that looks like that?

*Little kids:* If the guy takes the 1st turn, then the cat goes next, then the guy to repeat…who takes the 7th turn? *Bonus:* Who takes the 18th turn?

*Big kids:* If a 12-layer stack has 3 blocks in each layer, and they remove the center block from each layer and stack them in new 3-block layers on top, how many new layers do they add? *Bonus:* If then the top half of the blocks in this restacked tower (*not* half the layers!) come crashing down, how many layers are left standing? (Hint if needed: How many blocks does this tower have?)

Answers:

*Wee ones:* The blocks are rectangles, or “rectangular prisms” in 3D. See if you can find a 6-sided rectangle box!

*Little kids:* The guy, since 7 is an odd number. *Bonus:* The cat, since 18 is an even number.

*Big kids:* There are 4 new layers, since 12 blocks get removed and restacked. *Bonus:* The bottom 9 layers. There are 36 blocks in total, so the bottom 18 blocks stay standing. They take up 9 layers since the whole bottom 12 layers have just 2 blocks per layer.

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]]>The post Before You Pop It… appeared first on Bedtime Math.

]]>It’s Corn on the Cob Day, a great time to celebrate a very math-y food. For one thing, the kernels grow in nice neat rows, and any ear of corn will have an even number of rows in total. There are usually 16 rows, holding 800 kernels. Usually just 1 or 2 ears grow on each corn stalk, but in 2009 farmer Tyler Craig broke the world record with a plant that had 16 ears! Growing more ears is a good thing, since we use corn to make more than 3,500 other things, including foods like popcorn, cereal and marshmallows, and even non-food stuff like fireworks, glue, shoe polish, and plastic. Ew! We think the tastiest way to enjoy corn might be right off the cob.

*Wee ones:* Corn can grow in many colors: purple, green, blackish, bluish, red, white, and of course yellow. How many colors is that?

*Little kids:* If an ear of corn has to have an even number of rows, can it have 5 rows? *Bonus:* If an ear has 16 rows and you munch them one at a time until there are 10 left, what numbers do you say to count down the rows you eat?

*Big kids:* A bushel (8-gallon barrel) of corn has enough sugar to sweeten 400 cans of soda! How many cans can you sweeten with 2 bushels? *Bonus:* If you start at row 1 and eat every 3rd row of corn as you go 1 full time around a cob with 16 rows, how many rows do you eat without passing where you started?

*The sky’s the limit:* If an ear of corn has 800 kernels in 16 rows, how many in each row? (*Hint if needed:* To divide a number by 16, just cut it in half 4 times in a row.)

Answers:

*Wee ones:* 7 colors.

*Little kids:* No, since 5 is an odd number. *Bonus:* 16, 15, 14, 13, 12, 11.

*Big kids:* 800 cans. *Bonus:* 6 in total: you’ll eat rows 1, 4, 7, 10, 13, and 16.

*The sky’s the limit:* 50 kernels per row.

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]]>The post A Teeny Friend for Bambi appeared first on Bedtime Math.

]]>If you’ve ever seen a grown-up deer, either at a zoo or prancing through your neighborhood, you know that they’re big animals — smaller than a horse, but bigger than you are. But some types of deer are very tiny, and the tiniest is the pudu. This baby pudu was born at Queens Zoo in New York City. It stood just 6 inches tall at birth, and will grow to only 1 foot tall! (at the shoulder). It also weighed less than a pound, and a lot less than you weighed when you were born. Like other baby deer, the pudu will lose its spots. It will also grow antlers just 2-3 inches long. A big deer could scoop up a whole pudu with its antlers!

*Wee ones:* How many legs does that pudu have? Who has more legs, a pudu or you?

*Little kids:* A pound has 16 ounces. Who weighs more, a 1-pound pudu or a 12-ounce bottle of water? *Bonus:* If a 1-pound baby pudu grows to 13 pounds, how many pounds does it gain?

*Big kids:* The pudu will reach its full 12 inches at the shoulder in just 3 months. If your pet dog’s shoulder height is double that, how tall is your dog at the shoulder? *Bonus:* If YOU doubled your height these next 3 months, how tall would you be?

Answers:

*Wee ones:* The pudu has 4 legs, so it has more legs than you.

*Little kids:* The pudu, but not by much! *Bonus:* 12 more pounds.

*Big kids:* 24 inches. *Bonus:* Different for everyone…take your height in inches and double it (or add that number to itself)!

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]]>The post How to Dance in 100 Places appeared first on Bedtime Math.

]]>Do you like to dance? Do you know any cool moves? People who like to dance like to learn hundreds of new steps, as many as they can. This guy took it one step further: Matt Bray danced in 100 places. He danced each move in 3, 4 or even 5 places, then connected the pieces of video perfectly with the music. He looks like he just keeps dancing while the scenery changes. Then he switches to the next step in the routine, a hip hop step or a moonwalk, and does that in a few more places. See if you can guess where he is in each part of the video — and see if you can dance like him!

*Wee ones:* If you do 8 big hops to the music, what numbers do you say to count them? Try it!

*Little kids:* If Matt moonwalks 3 steps in the first spot, 2 in the next, and 4 in the one after that, how many steps has he moonwalked? *Bonus:* If he did all but 2 of those with his right foot, how many did he do with his right foot?

*Big kids:* If it took Matt 2 hours to film in each spot except for 5 hours at the very last place, how long did it take him to film in 100 places? *Bonus:* If you want to dance each move in exactly 4 places, how many cool moves do you need to know to cover 100 places?

__Answers:__

*Wee ones:* 1, 2, 3, 4, 5, 6, 7, 8.

*Little kids:* 9 steps. *Bonus:* 7 steps.

*Big kids:* 203 hours: It would have been 200, but switching the last 2 hours to 5 adds 3. *Bonus:* 25 moves.

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]]>The post Ride That Lobster! appeared first on Bedtime Math.

]]>When you draw a picture of some creature, wouldn’t it be cool if it could come to life and hang out with you? That’s just about what happened in this story from our fan Laurel P. When folks built a new merry-go-round in the Boston area, artist Jeff Briggs asked kids to draw their favorite animals from the wildlife around them. Then he turned their pictures into clay shapes, which became the seats on the merry-go-round! This shows a drawing of a lobster that then became a lobster you can ride. Other New England animals included turtles, seals, and hawks. Not your usual merry-go-round horses!

*Wee ones:* A lobster has 8 legs, while you have 2. Who has more?

*Little kids:* If the merry-go-round has a seal, then a turtle, then a seal, then a turtle, then a seal…what next 3 animals would keep the pattern? *Bonus:* In a set of 10, how many would be turtles?

*Big kids:* If the merry-go-round has an inner ring of 18 animals, a ring of 20 animals in the middle, then 22 animals on the outside, how many does it have — and what’s a shortcut to add them? *Bonus:* If the inside ring always has 2 fewer animals than the middle ring, and the outer has 2 more than the middle, how many in each ring would add up to 90 animals?

__Answers:__

*Wee ones:* The lobster has more legs.

*Little kids:* Turtle, seal, turtle. *Bonus:* 5 turtles (half the total).

*Big kids:* 60 animals. If you moved 2 animals out of the outer ring into the inner one, you’d have 20+20+20. *Bonus:* 28 animals, then 30, then 32…and 30 more people get to ride!

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