Math Teachers at Play #85

Posted on by Denise Gaskins

[Feature photo by Tomruen via Wikimedia Commons.]

Do you enjoy math? I hope so! If not, browsing the articles linked in this post just may change your mind.

Welcome to the 85th edition of the Math Teachers At Play math education blog carnival‌—‌a smorgasbord of links to bloggers all around the internet who have great ideas for learning, teaching, and playing around with math from preschool to pre-college.

By tradition, we start the carnival with a short puzzle or activity. But if you would like to jump straight to our featured blog posts, click here to see the Table of Contents.

Let the mathematical fun begin!

Continue reading Math Teachers at Play #85

Math Game: Thirty-One

Posted on by Denise Gaskins

Math Concepts: addition to thirty-one, thinking ahead.
Players: best for two.
Equipment: one deck of math cards.

How to Play

Lay out the ace to six of each suit in a row, face-up and not overlapping, one suit above another. You will have one column of four aces, a column of four twos, and so on‌—‌six columns in all.

The first player flips a card upside down and says its number value. Then the second player turns down a card, adds it to the first player’s number, and says the sum.

Players alternate, each time turning down one card, mentally adding its value to the running total, and saying the new sum out loud. The player who exactly reaches thirty-one, or who forces the next player to go over that sum, wins the game.

31-Game

Continue reading Math Game: Thirty-One

Math Game: Chopsticks

Posted on by Denise Gaskins

Math Concepts: counting up to five, thinking ahead.
Players: two or more.
Equipment: none.

How to Play

Each player starts with both hands as fists, palm down, pointer fingers extended to show one point for each hand. On your turn, use one of your fingers to tap one hand:

  • If you tap an opponent’s hand, that person must extend as many extra fingers on that hand (in addition to the points already there) as you have showing on the hand that tapped. Your own fingers don’t change.
  • If you force your opponent to extend all the fingers and thumb on one hand, that makes a “dead hand” that must be put behind the player’s back, out of the game.
  • If you tap your own hand, you can “split” fingers from one hand to the other. For instance, if you have three points on one hand and only one on the other, you may tap hands to rearrange them, putting out two fingers on each hand. Splits do not have to end up even, but each hand must end up with at least one point (and less than five, of course).
  • You may even revive a dead hand if you have enough fingers on your other hand to split. A dead hand has lost all its points, so it starts at zero. When you tap it, you can share out the points from your other hand as you wish.

The last player with a live hand wins the game.

When a two-points hand taps a one-point hand, that player must put out two more fingers.
When a two-points hand taps a one-point hand, that player must put out two more fingers.

Continue reading Math Game: Chopsticks

April 2015 Math Calendar

Posted on by Denise Gaskins

AprilMathCalendar

Six years ago, my homeschool co-op classes had fun creating this April calendar to hand out at our end-of-semester party. Looking at my regular calendar today, I noticed that April this year starts on Wednesday, just like it did back then. I wonder when’s the next time that will happen?

A math calendar is not as easy to read as a traditional calendar — it is more like a puzzle. The expression in each square simplifies to that day’s date, so your family can treat each day like a mini-review quiz: “Do you remember how to calculate this?”

The calendar my students made is appropriate for middle school and beyond, but you can make a math calendar with puzzles for any age or skill level. Better yet, encourage the kids to make puzzles of their own.

How to Use the Math Calendar

At home:
Post the calendar on your refrigerator. Use each math puzzle as a daily review “mini-quiz” for your children (or yourself).

In the classroom:
Post today’s calculation on the board as a warm-up puzzle. Encourage your students to make up “Today is…” puzzles of their own.

As a puzzle:
Cut the calendar squares apart, then challenge your students to arrange them in ascending (or descending) order.

Help Us Make the Next Math Calendar

If you like, you may use the following worksheet:

Submission details here: Kids’ Project — More Math Calendars?

Happy Birthday, General Relativity

Posted on by Denise Gaskins

Don’t forget that Pi Day is also Albert Einstein’s birthday! And this year marks the 100th anniversary of his Theory of General Relativity. So Science Magazine has a special Einstein issue online, featuring this interactive comic:

comic-image

You may also enjoy:

Pi: Who Needs That Many Digits?

Posted on by Denise Gaskins

From Numberphile: Pi is famously calculated to trillions of digits – but Dr. James Grime says 39 is enough.

How you round it off makes a difference:

An extra note from Dr. Grime: “Since pi39 ends in 0, you may think we could use pi38 instead, which has even fewer digits. Unfortunately, the rounding errors of pi38 are ten times larger than the rounding errors of pi39 — more than a hydrogen atom. So that extra decimal place makes a difference, even if it’s 0.”

Pi and Buffon’s Matches

Posted on by Denise Gaskins

From Numberphile: Dr Tony Padilla’s unique (and low budget) twist on the Buffon’s Needle experiment to learn the true value of Pi.

For a kid-friendly version of this experiment, try throwing food:

Do you have a favorite family activity for celebrating Pi Day? I’d love to hear it!

Pi Makes a River Bend

Posted on by Denise Gaskins

From Numberphile: “Sinuosity is a measure of how ‘bendy’ a river is. It is the length of the river divided by the direct route. Featuring Dr. James Grime.”

Update

After posting this video, Dr. Grimes and Lawrence Roberts began collecting and analyzing data about real-world rivers. It turns out the pi theory of sinuosity is too simple. Read about their results: