The post A Backwards Day appeared first on Bedtime Math.

]]>A palindrome is a word that is spelled the same backwards and forwards, like toot and racecar. Can you think of any others? It turns out *numbers*can do the same thing — like today’s date! Today is written as 8/18/18, which means the 18th day of the 8th month of the year (August). In fact, we’re in a week-long stretch where every day is a palindrome, starting with 8/10/18 all the way until 8/19/18. Don’t forget, 8/1/18 was a palindrome, too! We’ve been having cool stretches of dates for the past few years, like 7/13/17, and 6/11/16…but these streaks don’t happen every year forever, as we’ll find out below. See if can you figure out when the next streak will happen!

*Wee ones:* How do you say “123” in backwards order?

*Little kids:* If you say “221” in backwards order, is it the same or different? How about 454? *Bonus:* How old will you be the next time your age is the same backwards and forwards?

*Big kids:* After 8/18/18, what’s the next date that will be a palindrome? *Bonus:* How long is that from our last palindrome this year?

*The sky’s the limit:* If you’re allowed to write both the month and year as 2 digits, when’s the first year when we won’t have any palindromic dates? (For example, in 2020 you can write February as 02).

Answers:

*Wee ones:* 321.

*Little kids: *221 then reads 122, so it’s not a palindrome. But 454 does work! *Bonus:* Different for everyone…any single digit works, like 7, 8 or 9! Or your next age might be 11, or 22…or 101!

*Big kids:* The next one will be 9/1/19. *Bonus:* Counting from 8/19/18, that’s 1 year and 13 days later (378 days).

*The sky’s the limit:* We’ll have the same kinds of dates in 2019 (/10/19, 9/11/19…), and in 2020 we can have them in February (02/1/20 through 02/9/20, plus 02/11/20). We’ll also have a couple in 2021 (for example: 1/2/21, 1/21/21, and 12/1/21 through 12/9/21, as well as 12/11/21 and 12/22/21). Then in 2022 we’ll have 2/2/22, 2/20/22, 2/21/22 and so on. That’s true throughout the ’20s, with dates like 3/20/23, all the way through 9/29/29. In 2030 we start over with 03/1/30, then 1/3/31. This pattern will continue through the ’40s, ’50s, all the way to 9/9/99 in 2099. 2100 is the first year we won’t have one, because we can’t have 0/0/00!

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]]>The post The Wake ‘n Bacon appeared first on Bedtime Math.

]]>Sometimes it’s hard to wake up in the morning if you’re really sleepy. But the smell of yummy breakfast might get you out of bed. So how about an alarm clock that wakes you with the smell of bacon? That’s right: the Wake ‘n Bacon Alarm Clock not only buzzes to wake you up, but also pops out a tray of hot, crispy bacon. At night you put raw bacon inside the clock (which of course is shaped like a pig). In the morning, 10 minutes before your alarm goes off, the clock heats up and cooks the bacon. When the buzzer rings, the clock serves up your bacon from the side of the pig’s head. We heard about this clock years ago, but have still never seen one ourselves, even though this has to be the best invention ever. Someone should build it to make pancakes, too: the Wake ‘n Cake ‘n Bacon!

*Wee ones:* If you put 4 strips of bacon in your Wake ‘n Bacon, but then throw in 1 more, how many strips of bacon will it make?

*Little kids:* If you put in 3 strips of bacon for yourself and twice as much for the rest of your family, how many strips of bacon pop out? *Bonus:* If it could make pancakes, too, and you make 2 strips of bacon, then 3 pancakes, then 2 strips of bacon…what’s the 10^{th}thing you make?

*Big kids:* If you set you alarm for 7:05 am, at what time does the bacon start cooking if it needs 10 minutes? *Bonus:* If you like softer bacon and set it to cook just 8 minutes each day, how much time does your Wake ‘n Bacon spend cooking bacon over 1 week?

Answers:

*Wee ones:* 5 strips of bacon.

*Little kids:* 9 strips, since you make 6 for the rest of your family. *Bonus:* A pancake, since it’s the 5^{th} thing in a set of 5.

*Big kids:* At 6:55 am (5 minutes before 7 am). *Bonus:* 56 minutes, or almost an hour a week.

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]]>The post Feather Bedhead appeared first on Bedtime Math.

]]>We just love this guy’s hairdo. He’s an Egyptian vulture, also known as “the Pharaoh’s chicken” after Egypt’s long-ago kings. Aside from his crazy feather bedhead, he also has a very pointy-looking beak, and he’s very smart with how he uses it. Egyptian vultures are one of the few birds that hold objects and use them as “tools.” Vultures usually eat animals that are already dead – yuck! But they also eat other things, like the eggs of other birds. The vulture holds a pebble in its mouth and pounds it like a hammer on the egg to open it and eat it. Also, vultures use their beaks to roll up wool on twigs when building their nests. Now, if we could just teach him how to use a hairbrush…

*Wee ones:* How many eyes does our Egyptian vulture friend have?

*Little kids:* An Egyptian vulture’s wings stretch 3 times as far as his body length! Lie down with your arms to the sides, and have a grown-up mark the end of each hand with a book or toy. Now turn to put your head near one marker, and your feet by the other. Which is longer, your body or your armspan? *Bonus:* A female Egyptian vulture lays 2 brick-red eggs each year. If she’s been laying eggs all *your* life, how many eggs has she laid altogether? (Don’t worry about half-years!)

*Big kids:* If you take 7, add 2, triple what you get, and subtract 6, you get the number of years Egyptian vultures live. How long is that? *Bonus:* When Egyptian vultures “migrate” (fly north or south for the season), they can fly 300 miles in 1 day. How many miles could they fly in 1 week? (Hint if needed: What if they flew just 3 miles a day…then how about 30 miles a day…)

*The sky’s the limit:* If an Egyptian vulture hammers an egg, then rolls up a twig, then says “ca-caw!”, then hammers, rolls a twig, ca-caws, and so on to repeat the pattern, what’s its 92nd move?

Answers:

*Wee ones:* 2 eyes.

*Little kids:* They might not be exactly the same, but they’ll be close! *Bonus:* Different for everyone…multiply your age by 2.

*Big kids:* 21 years. You get 9, then 27, then 21. *Bonus:* 2,100 miles.

*The sky’s the limit:* Rolling up a twig. 92 is 2 more than a very clear multiple of 3 (90), so it’s the 2^{nd} move in the set.

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]]>The post That’s One Heavy Ocean appeared first on Bedtime Math.

]]>Every day we stand up and walk around on the ground. That’s because we aren’t fish. But 3/4 of Earth is covered with water. So our friend Parker M. asked, how much does the ocean weigh? Well, water’s really heavy: if you had a box 1 foot wide, 1 foot long and 1 foot tall filled with water, it would weigh about 62 1/2 pounds! Scientists’ best guess is that there are 326 million cubic *miles* of water, meaning boxes a whole mile wide, a mile long and a mile tall. Each side of a cube that size is 5,280 feet long, so there are 5,280 x 5,280 x 5,280 little 1-foot boxes in each of those cubic miles…we get 47,986,532,352,000,000,000 of those, or nearly 48 *quintillion*. Multiply by 62 1/2 pounds for each of those, and that weighs 3 *sextillion* pounds. We’re glad we could figure this out without weighing it cup by cup!

*Wee ones:* Plug a sink, turn on the water while you count to 5, then turn it off. Is the sink a little bit full, half full, or totally full?

*Little kids:* If you drink a cup of water at breakfast, then lunch, then dinner, plus 3 more cups in the afternoon, how many cups do you drink each day? *Bonus:* How many more would you need to drink a half-gallon (8 cups)?

*Big kids:* 1 gallon of water weighs about 8 pounds. How many gallons of water match your weight? (Hint if needed: 8 is 2 x 2 x 2, so to divide by 8, you just cut in half 3 times in a row.) *Bonus:*How much does a 40-gallon bathtub of water weigh, if each gallon weighs about 60 pounds?

Answers:

*Wee ones:* It should probably be only a little bit full.

*Little kids:* 6 cups. *Bonus:* 2 more cups.

*Big kids:* Different for everyone…divide your weight by 8, or see how many 8s you need to add up to match your weight. *Bonus:* 2,400 pounds!

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]]>The post Chalk Art Gone Wild appeared first on Bedtime Math.

]]>Have you ever drawn with sidewalk chalk? What’s awesome is that you have a whole sidewalk for your picture, so that picture can be huge – much bigger than on a piece of paper. It got *really* huge when more than 6,000 people together drew the world’s largest chalk pavement art. Those little blocks in the corner of the photo are buildings! Drawn in California in 2008, the picture covered 90,000 square feet. It took just 15 hours, and what’s really cool is that more than 4,000 of those people were kids. In 2015 an even bigger picture was drawn by 5,678 kids. But we still love this lizard. Next time you go outside, you could turn your driveway or sidewalk into your own giant picture – at least until it rains.

*Wee ones:* How many feet can you count on that lizard?

*Little kids:* If you and 4 friends draw one giant toe, how many of you are drawing? *Bonus:* If you draw for 3 hours starting at 9:00 in the morning, at what time do you finally take a break?

*Big kids:* If that lizard has 4 feet and 4 toes on each foot, how many more toes does it have than you do? *Bonus:* If 6,000 people drew this art and each one used up 3 boxes of chalk, how many boxes were used?

*The sky’s the limit:* The area of a rectangle is its width in feet times its length. If that perfectly square picture covers 90,000 square feet, how wide is the square? (Remember a square means that width and length are the same number.)

Answers:

*Wee ones:* 4 feet.

*Little kids:* 5 people. *Bonus:* At 12:00 noon.

*Big kids:* 6 more, since it has 16 toes and you have just 10. *Bonus:* 18,000 boxes.

*The sky’s the limit:* 300 feet. We know 3 x 3 is 9, and since there are 4 zeroes, we need 2 zeroes on each 3 to make 4 zeroes once we multiply.

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]]>The post The Horse That Could Ride You appeared first on Bedtime Math.

]]>Wait — is that a real horse next to that dog? It is, and her name is Thumbelina. She’s the smallest horse in the world, standing less than 18 inches tall. She weighs 57 pounds, which might be close to what a kid weighs! In fact, her parents are miniature horses, weighing around 175 pounds – about the same as a human grown-up. Normal-sized horses can weigh 1,000 pounds or more, so these furry friends are tiny. To top it off, Thumbelina was born a dwarf: she won’t ever grow to her parents’ full adult size. She’s so small that if you stood a loaf of bread on end, it would reach to her shoulders. Meanwhile, the world’s BIGGEST horse is Big Jake. He stands 6 feet 11 inches tall, and weighs around 2,600 pounds. That’s way more than a person, even a grown-up!

*Wee ones:* Tiny Thumbelina has 2 front feet and 2 back feet, like any horse. How many horseshoes does she need to wear?

*Little kids:* Horses like oats. If you feed Thumbelina 2 bowls of Cheerios for breakfast, for lunch and for dinner, how many bowls will she eat today? *Bonus:* The seat of a kid’s chair is around 15 inches high. At 18 inches Thumbelina is barely taller — but by how much? Count up from 15 if it helps!

*Big kids:* If Thumbelina is 18 inches tall, how much shorter than you is she? *Bonus:* If a bunch of 200-pound dwarf horses want to play tug-of-war against Big Jake, how many dwarfs need to pile up to weigh as much as Jake?

Answers:

*Wee ones:* 4 horseshoes.

*Little kids:* 6 bowls. *Bonus:* 3 inches.

*Big kids:* Different for everyone…find out your height in inches, then subtract 18. *Bonus:* 13 horses.

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]]>The post Speed Stackers appeared first on Bedtime Math.

]]>As you learn to do new things, sometimes you find out you’re really fast at them. You might be a fast jungle-gym-climber, or Lego-snap-togetherer, or ice-cream-eater. Well, one fun thing people do really fast is cup-stacking. They race to stack regular old plastic cups into pyramids, without knocking anything over. So of course, now people race at this against each other. In official speed-stacking, players are given 12 cups. First you build a big 6-cup pyramid with 2 little 3-cup triangles on either side. Then you shove all the cups back together, then take them apart to build two 6s. Then you build a 10-cup pyramid, and finally you put the cups back in their starting spots. Watch this kid’s awesome video and try for yourself…you might find out you’re a speed stacker, too!

*Wee ones:* If you stack a 6-cup pyramid and your friend stacks a 3-cup one, who stacked more cups?

*Little kids:* If you’ve stacked your 6-cup pyramid and first 3-cup pyramid, how many cups have you stacked? *Bonus:* If the winner stacks in 12 seconds, your friend stacks in 16 seconds, and your time is exactly halfway between, how fast do you stack?

*Big kids:* If you stack 6 cups, then 3 cups, then 10, then 6 again and 3 again to start over…what size pyramid do you stack on the 19^{th} time? See if you can get it without counting all the way up! *Bonus:* If you stack a 6-cup and 2 3-cups, then 2 6-cups, and then a 10-cup, and you take 1/2 second to place each cup, how fast do you stack all that?

Answers:

*Wee ones:* You stacked more cups.

*Little kids:* 9 cups. *Bonus:* 14 seconds.

*Big kids:* 6 cups, because it’s at the start of a new set of 3 moves. *Bonus:* 17 seconds, since you placed 34 cups.

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]]>The post Soccer for Your Car appeared first on Bedtime Math.

]]>It’s easy to kick a soccer ball, since it’s so much smaller than you. But try kicking one that’s as tall as your bedroom ceiling! Our fan and friend Tyler M. sent us a great video of Trackhoe Soccer, where cars and trucks play big soccer with an 8-foot-high ball. In regular “people” soccer, each team tries to kick the ball into the goal at the end of the field, while the other team tries to stop them. Here, cars are the players, and 2 big yellow diggers (“excavators”) are the goalies. Cars and trucks can’t kick, of course, so they drive, skid and turn to push the ball. We just hope they don’t crash into each other.

*Wee ones:* How many cars, trucks and diggers can you count on the soccer field?

*Little kids:* What do you call the 5-sided black shapes on the soccer ball? *Bonus:* If the car team scores 1 goal, then the truck team scores 2 goals, then cars score 1, then trucks score 2…which team scores the 10^{th} goal to keep the pattern?

*Big kids:* Trackhoe soccer is played once a year, and this 2018 game is the 5^{th} one! In what year was the 1^{st} game? *Bonus:* If there are 18 players out there, and there are twice as many white vehicles as colored ones, how many white vehicles are there?

*The sky’s the limit:* If there are equal numbers of cars and trucks, and 1/2 the cars and 2/3 the trucks are red, and there are 2 more red trucks than red cars…how many trucks are there?

Answers:

*Wee ones:* 9 vehicles: 8 “players” and 1 digger.

*Little kids:* Pentagons. *Bonus:* The car team, since trucks will score goals 8 and 9.

*Big kids:* In 2014. Remember, you can’t just subtract 3, since that would bring you to year “zero” when there was no game. *Bonus:* 12 white and 6 colored. If there are twice as many whites, it’s like a set of colored cars and 2 more sets the same size, making 3 “sets” total.

*The sky’s the limit:* 2/3 of the number is 2 more than 1/2 of the same number. And the difference between 2/3 and 1/2 is 1/6. So 2 is 1/6 of the total, and there are 12 trucks.

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]]>The post Fingertip Frog appeared first on Bedtime Math.

]]>You may not believe it, but that cute, teeny frog on that coin is real. It’s smaller than a dime, a Cheerio from breakfast, or a cricket — when most frogs eat crickets for breakfast themselves! How did anyone find such a teeny frog? Two scientists, Christopher Austin and Eric Rittmeyer, were exploring a tropical forest when they heard a weird sound. They hunted through the forest floor, but couldn’t find the thing that was making the noise. Finally they just scooped up a bunch of leaves, stuffed them in a plastic bag, and took it home to look through it. Then the teeniest frog they had ever seen hopped out. Hopping is what this frog does best: it can leap 30 times the length of its own body. The best part is, if you want one as a pet, you can carry him around in your wallet.

*Wee ones:* Frogs usually have 4 “fingers” on each front foot. You have 5 fingers on each hand. Whose “hand” has more fingers?

*Little kids:* If 1 frog sits on a dime (10 cents) and another sits on a penny (1 cent), how many cents are the frogs sitting on all together? *Bonus:* How many more frogs on pennies would you need to make 14 cents total?

*Big kids:* If your hand is 6 inches long, and you can line up 3 frogs in an inch, how many frogs could you line up on your hand? *Bonus:* This tiny frog can leap 30 times its own length! If you could jump 30 times your length (height), how many feet would that be? (You can round your height to the nearest foot or half-foot…or try it in inches! *Hint if needed:* Multiplying by 30 is like multiplying by 3 and then by 10.)

Answers:

*Wee ones:* You have more fingers.

*Little kids:* 11 cents. *Bonus:* 3 more cents.

*Big kids:* 18 frogs. *Bonus:* Different for everyone…multiply your height in feet or inches by 30.

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]]>The post Snack Time for Horses appeared first on Bedtime Math.

]]>What are those giant rolls of brown stuff? They’re bales of straw, from a Picture of the Day on Wikimedia. Farm animals like horses and cows sleep on straw, so farms need to gather up a lot of it. Farms also need lots of hay for animals to eat: a horse needs to eat about 20 pounds of hay each day. That might be a quarter or a third of what *you* weigh! As you can see in this video, tractors make bales in a very cool way. They drag a baler behind them. Blades cut the stalks, then roll them up inside the machine. The back opens and out rolls the bale, like a chicken laying an egg. By the way, what’s the difference between hay and straw? Hay is alfalfa or grass, while straw is dried-out, leftover wheat stalks. Just like you don’t want to eat your pillow, horses don’t want to eat straw!

*Wee ones:* What shape does the front of a bale look like?

*Little kids:* What 3-D shape is the whole bale? *Bonus:* How many bales can you count in the field? Which one do you think is closest to the camera?

*Big kids:* Square bales of hay weighs 50 pounds. If each horse eats 20 pounds, how many horses can you feed enough food with 1 bale? *Bonus:* How many bales do you need to be able to feed an exact number of horses?

*The sky’s the limit:* If you make a bale with twice as wide a circle (but the same length), it will hold 4 times as much hay. If it’s 3 times as wide, it will hold 9 times as much hay. How many times as much hay would a bale 4 times as wide hold?

Answers:

*Wee ones:* A circle.

*Little kids:* A cylinder — the same shape as a can of food. *Bonus:* We think we see parts of 10 bales. The one that looks biggest is the closest.

*Big kids:* Just 2 horses. *Bonus:* 2 bales. That will give you 100 pounds, which can feed 5 horses.

*The sky’s the limit:* 16 times as much hay. Circles work like squares: if it’s 2 times as wide in every direction, it will cover 2 x 2 the area, or 4 times the area. So a circle (or square) 4 times as big in every direction will hold 4 x 4 as much area. If the height of the cylinder is the same, you’re stacking the same number of 1-foot tall layers; it’s just that they’re each 16 times as big. So you get 16 times the volume (space that the bale fills).

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