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Math Teachers at Play #35

35 is a tetrahedral number

Welcome to the Math Teachers At Play blog carnival — which is not just for math teachers.

Do you enjoy math? I hope so! If not, browsing these links just may change your mind. Most of these posts were submitted by the bloggers themselves; others are drawn from my overflowing Google Reader. From preschool to high school, there are plenty of interesting things to learn.

Let the mathematical fun begin…

Continue reading Math Teachers at Play #35

Our Power Outage Adventure

[Photo by Nestor Galina.]

Our power finally came back on this afternoon after a couple of cold, dark nights.

Staying Warm

We heated the house with candles and stove-top burners (propane). We found that if you get enough candles lit in a room, it really can make a difference, and the stove was able to keep the kitchen in the upper-50’s, even above 60 degrees at times, which was pretty comfortable. We dressed in lots of layers and wore gloves, drank a plenty of coffee and hot chocolate, listened to oldies on the battery-powered radio, and went to bed early each night. (Hooray for sleeping bags!)

Continue reading Our Power Outage Adventure

Quotable: What to Do When You’re Stuck

When a kid is feeling bad about being stuck with a problem, or just very anxious, I sometimes ask him to make as many mistakes as he can, and as outrageous as he can. Laughter happens (which is valuable by itself, and not only for the mood — deep breathing brings oxygen to the brain). Then the kid starts making mistakes. In the process, features of the problem become much clearer, and in many cases a way to a solution presents itself.

Maria Droujkova
Natural Math discussion of math club activities

Does It Work?

While I was collecting entries for the Math Teachers at Play #35 blog carnival, I ran across this post by Dave Lanovaz:

Babymath: Story Problem Challenge III

<a href="http://www.flickr.com/photos/goetter/2352128932/"Photo by Raphael Goetter via Flickr

Alex and Leon enjoyed their baby sister, but they were amazed at how much work taking care of a baby could be. One particularly colicky night, everyone in the family took turns holding the baby, rocking the baby, patting her back, and walking her around before she finally succumbed to sleep.

Then Alex collapsed on the couch, and Leon sank into the recliner. They teased each other with these story problems.

Continue reading Babymath: Story Problem Challenge III

Top 10 Posts of 2010

Cartoon showing baby representing New Year 190...
Image via Wikipedia

2011 will be a fantastic year — or at least, a prime one! (See these posts by Gary, Pat, and James.) But as we move into the new year, it’s also a good time to look back and to look ahead: What did we accomplished last year? And what comes next?

More specifically, for bloggers:

  • What did people like to read?
  • How can I give them more of it?

So here is my retrospective look at the most popular blog posts of 2010, along with related blogging goals (or dreams?) for 2011.

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2011 Mathematics Game

[Photo from Wikipedia.]

Two of the most popular New Year’s Resolutions are to spend more time with family and friends, and to get more exercise. The 2011 Mathematics Game is a chance to do both at once.

So grab a partner, slip into your workout clothes, and pump up those mental muscles!

Here are the rules:

Use the digits in the year 2011 to write mathematical expressions for the counting numbers 1 through 100.

  • All four digits must be used in each expression. You may not use any other numbers except 2, 0, 1, and 1.
  • You may use the arithmetic operations +, -, x, ÷, sqrt (square root), ^ (raise to a power), and ! (factorial). You may also use parentheses, brackets, or other grouping symbols.
  • You may use a decimal point to create numbers such as .1, .02, etc.
  • Multi-digit numbers such as 20 or 102 may be used, but preference is given to solutions that avoid them.

Bonus Rules
You may use the overhead-bar (vinculum), dots, or brackets to mark a repeating decimal.

You may use multifactorials:

  • (n!)! = a factorial of a factorial, which is not the same as a multifactorial
  • n!! = a double factorial = the product of all integers from 1 to n that have the same parity (odd or even) as n
  • n!!! = a triple factorial = the product of all integers from 1 to n that are equal to n mod 3

[Note to teachers: The bonus rules are not part of the Math Forum guidelines. They make a significant difference in the number of possible solutions, however, and they should not be too difficult for high school students or advanced middle schoolers.]

Continue reading 2011 Mathematics Game