The post Skating Through by a Hair appeared first on Bedtime Math.

]]>*Wee ones:* A roller skate has 2 wheels under your toes and 2 under your heel. How many wheels does the skate have?

*Little kids:* If you strap on 2 4-wheeled skates, how many wheels do you have? *Bonus:* If you then skate like Gagan under 2 cars and an 18-wheeler truck, how many wheels do they have?

*Big kids:* If Gagan took exactly 2 seconds to skate under each car, how long would the whole row of 39 cars take? *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 that row of 39 cars, 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 16 inches for the rest of them, how many cars don’t give Gagan any extra trouble?

Answers:

*Wee ones:* 4 wheels.

*Little kids:* 8 wheels. *Bonus:* 26 wheels.

*Big kids:* 78 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 Happy Birthday, New York! appeared first on Bedtime Math.

]]>*Wee ones:* If the guy who finds jewels in the gutter finds bits of diamond, ruby, platinum and gold, how many precious materials does he find?

*Little kids:* New York State turns 226 years old today. How old will New York State turn next summer? *Bonus:* If New York was the capital from 1785 to 1790, how many years was that? Count up if it helps! (Assume it became capital and lost the honor the same time of year.)

*Big kids:* In New York City a slice of pizza and the fare for a subway ride always cost the same, at least since 1960. Back then they each cost 15 cents, and in the 1970′s they each cost 35 cents. How much more did a slice or a ride cost in the 70′s? *Bonus:* In 2002 each one finally reached $2.00. How much had they gone up since the 70′s? (Reminder: 1 dollar has 100 cents.)

Answers:

*Wee ones:* 4 precious materials.

*Little kids:* 227 years old. *Bonus:* 5 years.

*Big kids:* 20 cents more. *Bonus:* $1.65 (a dollar and 65 cents, or 165 cents).

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

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

*Little kids:* If there are 4 kids playing xylophones and each one has 2 mallets, how many mallets do they 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:* The xylophones are laid out like a piano keyboard. If each one has 3 whole octaves of notes, where each has 7 white keys and 5 black keys, how many keys are on just one of these xylophones? *Bonus:* Even with just 4 xylophone players, how many notes would they have handy to play in total?

Answers:

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

*Little kids:* 8 mallets total. *Bonus:* E.

*Big kids:* 36 keys (3 sets of 12). *Bonus:* 144 keys.

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]]>The post From Dawn Till Dusk appeared first on Bedtime Math.

]]>Right now the Muslim calendar is in a very special month called Ramadan. It’s the ninth month and is sacred because that’s when the Prophet Muhammad received revelations, according to the Quran. To honor this period of time, grown-up Muslims who are healthy fast (skip eating) from dawn until dusk every day – but the timing of this is very different from place to place during summer and winter, because of sunrise and sunset timing. During the summer, the sun sets very late in the northern half of our planet since it’s tipped towards the Sun. Just north of the equator it’s a normal 12 hours of light, 12 hours of dark, but as you go north the sun sets later and later, until you reach the Arctic Circle where it’s daylight all 24 hours! In the meantime, right now there’s no sun at all at the South Pole. So Muslims who live very far north or south may follow the timing for current sunrise and sunset in Saudi Arabia, or use the sunrise and sunset timings of neighboring areas with proper day and night. But for everyone else, you have to do some math to find out exactly how long you’ll be fasting.

*Wee ones:* Which is longer, 10 hours of sunlight or 9 hours?

*Little kids:* If the sun rises at 7 am and sets exactly 12 hours later, at what time does it set? *Bonus:* If you finish eating 5 minutes before sunrise and start eating again 10 minutes after sundown on that day, for how long in hours and minutes do you fast?

*Big kids: *This year Ramadan began on Saturday, June 28 and will end with the festival of Eid al-Fitr on Monday, July 28. Given that Ramadan runs from evening to evening, for how many days will Ramadan last? *Bonus: *If you fasted a full 30 days every Ramadan, how many days would you fast over 5 years?

Answers:

*Wee ones:* 10 hours.

*Little kids:* At 7 pm. *Bonus:* 12 hours and 15 minutes.

*Big kids:* 30 days. *Bonus:* 150 days.

And thank you Radia M. for helping us with this math problem!

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]]>The post Math That’s a Hit! Make Your Own Piñata appeared first on Bedtime Math.

]]>Piñatas are always a “hit” with kids at outdoor picnics and parties. It’s one of the few chances kids get to whack at an object repeatedly with a stick — what’s more, instead of a getting a time-out for destroying the object, they get candy!

Store-bought piñatas are gorgeous, but they can easily cost $20 or more, so they’re best saved for special occasions. Making your own piñata is inexpensive, easy, and fun. The challenge is coming up with a piñata that doesn’t disintegrate after a single hit, but doesn’t require a couple of bodybuilders to get the treats out.

Figuring out how to make the perfect piñata is a great way to spend the afternoon with your kids. It’s also the perfect way to introduce your child to the Design-Build-Test concept. Because this requires such inexpensive materials, you can easily make several prototypes and have fun testing each one!

- cereal boxes and small pieces of cardboard
- newspaper, Styrofoam peanuts, and tissue paper
- scissors
- masking tape
- sturdy string for hanging
- crayons, markers, stickers, and other materials for decorating
- 1 cup of candy (individually wrapped)

Before actually building the piñata, encourage your child to think about the different shapes he or she can use. Let your child know that incorporating triangles into the piñata structure will help it withstand more hits, because triangles are extremely stable and do not change under pressure. Ask your child to consider 3D shapes containing triangles like these:

- square-based pyramid
- triangle-based pyramid
- diamond
- triangular prism

Encourage your child to explore different materials for constructing the piñata. A piñata constructed solely out of cardboard will be sturdy, but would it be too heavy for the string to hold? Having tissue paper or newspaper “windows” on each face would make the piñata lighter, but would it make the piñata too easy to break open?

Brainstorm with your kids about what kind of candy the piñata will hold: M&M’s or jelly beans? Gummy bears, lollipops, or gum? Get your child thinking about which candies are heavier than others. Do ten mini-packs of M&M’s weigh more than the same number of snack-sized bags of gummy bears? You want lots of candy inside that piñata, but you don’t want your piñata crashing to the ground even before anyone has had a chance to take a whack!

Ask your child to think about the best way to protect the candy inside the piñata from the force of the stick striking the piñata. Should the candy be wrapped in a layer of newspaper or tissue? Should the piñata be filled with Styrofoam peanuts as well as candy? The newspaper and/or Styrofoam form a safety cell (a reinforced area that protects the objects inside), which is also used in cars to protect passengers during a crash.

Use cereal boxes, cardboard, and newspapers to build the piñata, and use tape to hold it together. Make sure the piñata has a hollow opening to place the candies in. Your child can also decorate the piñata with crayons, markers, and stickers.

Hang the piñata from an overhanging tree branch or roof. Have your child hit the piñata with a wooden broomstick or bat (make sure the area is clear of other objects and people!). Record the number of hits it takes to break open the piñata. Was it too easy or too difficult to get the candy out? Did the piñata fall off the string before you could break it open? Did the candy come out broken or intact? Take your observations back to the drawing board and use them to build a better piñata the next time around!

*Be sure your piñata candy is fresh and tasty with this Bedtime Math problem.*

*Image licensed by Ingram Publishing*

The post Math That’s a Hit! Make Your Own Piñata appeared first on Bedtime Math.

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