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 The Purr-fect Seat appeared first on Bedtime Math.

]]>It’s nice to hang out on a couch with a pet. But sometimes those fuzzy animals can act like, well, animals. If a cat gets bossy, you might end up smooshed into one corner with a paw or tail in your face. So why not give cats their own couch? Lately people have been crocheting cat couches, like you see in the picture! Crocheting is a way of looping yarn into little knots, or stitches, to make fabric. It took this crocheter about 6 hours and 350 yards of yarn to make a couch, but now that kitty is sitting pretty!

*Wee ones: *If a person’s couch has 3 cushions and a cat’s couch has 2 cushions, which couch has more cushions?

*Little kids: *Animals put their feet on the couch, but we don’t! If 2 cats are sitting on a couch with you, how many paws are on the couch cushions? *Bonus: *If it takes 6 hours to make a kitty couch, and twice as long to make a couch for a big dog, how long does the big dog couch take?

*Big kids: *Different sizes of yarn will make different-sized stitches. Thick yarn might only need 6 stitches to make 2 inches of fabric. How many stitches of that yarn would it take to make 1 foot, or 12 inches, of fabric? *Bonus: *350 yards is a lot of yarn! If the playground at the park is on a rectangle 70 yards long and 40 yards wide, can that kitty couch yarn wrap all the way around the yard?

*The sky’s the limit: *Using the numbers in Big kids question, how many stitches are in those 350 yards of yarn?

Answers:

*Wee ones: *The person’s couch, because 3 is more than 2.

*Little kids: *8 paws, because 4 + 4 = 8. *Bonus: *12 hours, because 6 + 6 = 12, or 6 x 2 = 12.

*Big kids: *36 stitches. If 6 stitches = 2 inches, then there are 3 stitches in 1 inch. 3 x 12 = 36. Alternatively, because 2 goes into 12 6 times, you need 6 sets of 6 stitches, and 6 x 6 = 36. *Bonus: *Yes! The distance around the 4 sides of the playground is 70 + 40 + 70 + 40 = 220 yards.

*The sky’s the limit: *37,800 stitches. Since there are 3 feet in 1 yard, there are 36 x 3 = 108 stitches per yard. We can use partial products to simplify the multiplication from there: 350 x 108 = 350 x 100 + 350 x 8 = 35,000 + 300 x 8 + 50 x 8 = 35,000 + 2,400 + 400 = 37,800.

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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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]]>The post Whatever Floats Your Boat appeared first on Bedtime Math.

]]>Hey, why are those stuffed animals floating around in the pool? Well, because they can. They’re floating on little boats made of aluminum foil. Foil is thin, but it holds up the animals just fine. When you float something on a boat, the boat will sink just enough so that the water it “displaces,” or pushes out of the way, weighs the same as that object. If something weighs 1 pound, the boat will sink enough to push 1 pound (16 ounces) of water out of the way. If the sides of the boat are too low, the water will gush in over the top! But if the sides are high enough, then the boat floats. So if you want your furry friends to stay dry, just do the math. Weigh them first. Then test your boat with the same weight of pennies or rocks. That way you don’t have to have any sinking ships.

*Wee ones:* How many stuffed animals are floating in the pool? Look closely and count them!

*Little kids:* If the 3 lobsters each weigh 2 ounces, how much do they weigh together? *Bonus:* If the caterpillar weighs 9 ounces, how much more does he weigh than the lobster triplets?

*Big kids:* 11 pennies weigh about 1 ounce. If you need your boat to hold up a 5-ounce teddy bear, how many pennies does it need to be able to carry? *Bonus:* If you want to carry 5 of those teddy bears, and you’re testing your boat with 7-ounce rocks, how many rocks does it have to hold for you to know it can carry the bears?

Answers:

*Wee ones:* 4 stuffed animals.

*Little kids:* 6 ounces. *Bonus:* 3 more ounces.

*Big kids:* 55 pennies. *Bonus:* 4 rocks. The boat needs to hold 25 ounces, and 3 rocks will only prove that it can hold 21.

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]]>The post Lots of Dogs, Lots of Legs appeared first on Bedtime Math.

]]>What are all these dogs and people trying to do? The people are trying to run a 3-Legged Race while walking their dogs! But why? The dogs are all golden retrievers, and they’re at a summer barbecue for the Golden Retriever Club of Scotland. Scotland is where golden retrievers were first born. As for their silly owners, someone decided they should try a 3-legged race. 2 people stand next to each other, and strap together the 2 legs touching each other. So now instead of 4 legs all together, they have 3. That makes it tricky to walk: the person on the right has to step with the left leg exactly when the other person steps with her right leg. Now try to run like that while also handling a playful pup. Whoever won that race deserves a doggie treat!

*Wee ones:* If each team has a dog and 2 people, how many players are on a team?

*Little kids:* If each team has 2 people and a dog, how many legs on a team? *Bonus:* What kind of player would have to join them to make 10 legs in total?

*Big kids:* If 24 people and 13 dogs want to race, will they have leftover dogs or people once they pair up? *Bonus:* The club’s biggest barbecue ever had 222 dogs! How many furry paws did they have all together?

*The sky’s the limit:* If there are 81 players in total on a bunch of teams as described in the *Little kids *question, how many of each kind of player do they have?

Answers:

*Wee ones:* 3 players.

*Little kids:* 8 legs. *Bonus:* Another person, to add 2 legs.

*Big kids:* 1 leftover dog, since the 24 people need only 12 dogs. *Bonus:* 888 furry paws.

*The sky’s the limit:* 27 dogs and 54 people. There are 3 players on a team, so 81 players make 27 teams. Then each team has 1 dog and 2 people.

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]]>The post When the Plant Is the Boss appeared first on Bedtime Math.

]]>It must be tough being a plant, worrying that some bird or bug will munch on you. But some plants fight back: the pitcher plant eats bugs! How does it do this? The plant has tube shapes filled with a sweet, sticky liquid. Ants and flies that dare to come close slide down the leaves into the pool, and can’t get out. Eventually they mix into the liquid and disappear; that’s how the plant “eats” the vitamins. So our friend James H. asked, how many bugs can a pitcher plant eat in a year? (and sent a photo of his own pet plants!) We haven’t found exact numbers, but one scientist figured out that some plants can catch up to 20 bugs at a time!

*Wee ones:* If a plant eats breakfast, lunch, and dinner just like you do, how many meals in a day is that?

*Little kids:* If the plant eats an ant, then a fly, then an ant, then a fly…what’s the 8^{th} bug it eats? *Bonus:* How many flies has it eaten by then?

*Big kids:* If a pitcher plant eats 20 bugs in each meal 3 times a day, how many does it eat in a day? *Bonus:* If it kept that up every day, about how many would it eat in a year? You can round to 400 days to make a quick guess! (Hint if needed: How many would it eat in 4 days…then see how many in 40 days…then try 400.)

Answers:

*Wee ones:* 3 meals.

*Little kids:* A fly. *Bonus:* 4 flies.

*Big kids:* 60 bugs a day. *Bonus:* 24,000 bugs!

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]]>The post The Secret Formula for Fighting Fires appeared first on Bedtime Math.

]]>Firefighters get hot, but they may be the coolest heroes out there. Not only do these brave people save other people’s lives, but they need to do math to face the danger. When we at Bedtime Math talked to firefighter Joe Spych, he told us a secret about fire hydrants: the color tells you how fast they pump water. In one set of towns, a red cap color means the hydrant pumps less than 500 gallons per minute (GPM), orange means between 500-999 GPM, green means 1000-1499 GPM, and blue gushes out 1500 GPM or more. This matters because you need a gallon of water to put out every 3 square feet that’s on fire. By the way, a hose spraying 300 gallons of water a minute can fill about 8 bathtubs at once! But let’s see how much fire it can put out.

*Wee ones:* Plug your sink, then turn on the water and count to 10. Turn it off. Is the sink a little full, halfway full, or mostly full?

*Little kids:* If a fire truck has 5 “attack lines” (hoses) and you hook on 1 more, how many lines does it have now? *Bonus:* Which pumps water faster, a red hydrant at 90 gallons per minute, or an orange hydrant at 600 gallons per minute?

*Big kids:* If a rug that’s 10 feet wide and 9 feet long is on fire, how many square feet is that? (Imagine 10 rows of 1-foot-wide squares, with 9 squares in each row.) *Bonus:* If a gallon of water can put out 3 square feet of fire, how many gallons do you need to put out that fire?

__Answers:__

*Wee ones:* Most sinks will be only a little bit full, but yours might be different!

*Little kids:* 6 attack lines. *Bonus:* The orange hydrant pumps faster.

*Big kids:* 90 square feet. *Bonus:* 30 gallons, which is almost 1 bathtub of water!

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]]>The post A Song Every Minute appeared first on Bedtime Math.

]]>Do you like to sing? Do you have a favorite song? Music is like dessert: we don’t *have* to have it to stay alive, but we love it so much that someone is always making more. So our friend Elijah B. asked, how many songs are there in the world? That must be a big number, since anyone can write a new song – maybe you’ve even made up a song yourself! So we don’t know every song ever written. But a company called Gracenote keeps a list of all the songs out there: it had 79 *million* songs on it as of 2011. To get a sense of that number, 79 million minutes is about 150 years…so if most of the songs are from the year 1866 onward, that’s 1 new song every minute. Either way, it’s hard to learn the words to all of them!

*Wee ones:* Can you sing “la la la”? Sing the word “la” 6 times!

*Little kids:* If you have 2 favorite songs, and one runs 3 minutes long and the other is 2 minutes longer, how long is the 2nd song? *Bonus:* If you sing both songs one after the other, how long does that take?

*Big kids:* Humans started counting about 9,000 years ago, but started using an alphabet 4,000 years later. How many years ago did the alphabet start? *Bonus:* If you add together those 2 chunks of time (9,000 and 5,000), then subtract 2,000, then cut in half, you get the number of years ago that Egyptians had harps and flutes to play songs. How many years ago was that?

*The sky’s the limit:* If we have 81,000,000 songs by today, and humans wrote all but 1,000,000 of them in the last 100 years, how many songs have been written each year in the last 100 years if it’s equal every year?

Answers:

*Wee ones:* La la la, la la la!

*Little kids:* 5 minutes long. *Bonus:* 8 minutes.

*Big kids:* 5,000 years ago. *Bonus:* 6,000 years ago.

*The sky’s the limit:* 800,000 songs each year, since 80,000,000 songs were written in 100 years.

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]]>The post Tongue Twister for Your Eyes appeared first on Bedtime Math.

]]>Does this picture look right to you? An “optical illusion” is a shape or pattern that looks different from what was actually drawn. Straight lines that look curved, boxes that look flipped inside out…stuff like that. Well, here’s one that trips up your eyes along with your tongue! Starting in the top row of the picture, say the *color* of each word’s letters, instead of reading the word itself. How fast can you say all the right colors? It starts off all well and good, because the words and their colors match. But soon the words start showing up in colors that don’t match what they say. You keep wanting to read the words instead of saying the colors. See if you can trick your brain into behaving!

*Wee ones:* How many times does the word “red” show up in red letters like it should? Count them!

*Little kids:* Which row has the most words in it? *Bonus:* There are 5 purple-colored words, and 5 words that really are the word “purple” — and 1 of those words is in both groups (a purple “purple”). How many words is that in total?

*Big kids:* If you can get through each of the 8 rows in 3 seconds with no mistakes, how fast can you say the whole puzzle? *Bonus:* If you have 3 words — red, blue, and green — and those 3 colors, how many ways can you use all 3 colors to write those words without any word matching its own color?

Answers:

*Wee ones:* 2 times (once in each of the first 2 rows).

*Little kids:* They’re all the same, at 4 words each! No row has more words than any others. *Bonus:* 9 words, since it would be 10 if the 2 groups didn’t share any words.

*Big kids:* In 24 seconds. *Bonus:* Only 2 ways: BGR, and GRB. The word red can be only blue or green. For each of those choices, 1 of the remaining colors will match 1 of the remaining 2 words, so instead of having 2 different orders for placing the last 2 colors, there’s only 1 way for each choice.

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]]>The post A Sandwich That’s Actually Cool appeared first on Bedtime Math.

]]>Today is Ice Cream Sandwich Day! This sweet treat was invented in the early 1900s in New York City, when an ice-cream cart guy mashed vanilla ice cream between two thin cookies. By the way, the ice cream cone was invented around the same time, by wrapping a waffle around the scoop. Then the sandwich took new forms, like the chocolate-chip Chipwich in 1981. But as New York Times writer Ligaya Mishan found out, New York City alone has sandwiches made with coconut-jackfruit ice cream, ice cream flavored with grown-up liqueurs, and open sandwiches with no top layer at all. Mix and match your own cookies and ice cream to invent your own cool treat!

*Wee ones:* If an ice cream sandwich has a cookie, then a layer of ice cream, then another cookie, how many layers does it have?

*Little kids:* How many complete sandwiches can you make if you have 7 chocolate chip cookies handy? *Bonus:* How many would you need to make 7 *sandwiches*?

*Big kids:* If you have 4 kinds of cookies — sugar, Oreos, chocolate-chip, and oatmeal — and 4 flavors of ice cream — coconut, mint, peanut butter, and pistachio — how many wild cookie-ice cream sandwich combos can you make? (Assume each sandwich uses 2 of the same cookie.) *Bonus:* When did the Chipwich, born in 1981, have its 25th birthday?

Answers:

*Wee ones:* 3 layers.

*Little kids:* Just 3, since that will use 6 cookies; you’d need 8 to make 4 sandwiches. *Bonus:* 14 cookies (2 cookies apiece).

*Big kids:* 16 kinds, since each of the 4 pairs of cookies can go with any of the 4 flavors. *Bonus:* In 2006.

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