# Math Teachers at Play #35

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…

## TRY THIS PUZZLE

By tradition, we start the carnival with a puzzle in honor of our 35th edition:

• Take a piece of graph paper with 1/2″ squares, and cut it apart along the lines. Separate these squares into sets of six.
• Arrange each set so that all the squares touch sides with at least one other square. These are called hexominoes.
• Glue them to a piece of construction paper, so they don’t get mixed up. Try not to make any two patterns the same. Patterns count as the same if you can rotate or flip them to make them match.
• Can you find all 35 possibilities?
• Which of the hexominoes have an axis of symmetry? Which have rotational symmetry?
• Which of them could be folded up to make a cube?

## ELEMENTARY CONCEPTS

[Photo by Pink Sherbet Photography.]

There was an old man who said, “Do
Tell me how I should add two and two.
I think more and more
That it makes about four —
But I fear that is almost too few.”

The Professor said, “Now I’ll tell you
A fact known to only a few
Men and women alive.
Two plus two equals five!
For large enough values of two.”

## ARITHMETIC

[Photo by pranav.]

A dozen, a gross, and a score
Plus three times the square root of four
Divided by seven
Plus five times eleven
Is nine squared and not a bit more.

— Leigh Mercer

• And speaking of unit conversions, Michael P has “fun with some weird-sounding units, such as butts, nibbles and siriometers, culled from wikipedia” in his blog post I like butts.
• I love the games that John Golden invents, and his Integer Games were perfect to round out Kitten’s math lessons this week.

## BASIC ALGEBRA & GEOMETRY

[Photo by EricGjerde.]

If A equals B (so I say),
And we multiply both sides by A,
Then we’ll see that A squared,
When with AB compared,
Are the same. Remove B squared. Okay?

Both sides we will factorize. See?
Now each side contains A minus B.
We’ll divide through by A
Minus B, and ole!
A plus B equals B. Oh whoopee!

But since I said A equals B,
B plus B equals B, you’ll agree?
So if B equals one,
Then this sum I have done,
Proves that two equals one. Q.E.D.

• In a word problem Tuesday, Kitten forgot how to find the area of a circle. Time for a hands-on lesson, cutting up a paper plate — and together we’ll read Alexander Bogomolny’s post: Area of a Circle.

[Photo by quapan.]

When you cut Apollonius’ cone
There’s a circle, but it’s not alone.
A parabola, new,
A hyperbola, too,
And a perfect ellipse will be shown.

— Montgomery Phister

• Sam Alexander offers his Prenex Normal Form Generator, “A calculator which finds prenex normal forms of formulas. Might be useful for teaching basic first-order logic courses.” Does anyone really get to that in high school? All I remember from logic is Venn diagrams and truth tables.

## RECREATIONAL MATHEMATICS

[Photo by fdecomite.]

Limerick Problem #1:
Three different one-digit primes
produce me, if you’re using times;

Limerick Problem #2:
There once was a cube ’twas found
Whose two digits, when switched clear around,
Was the product (quite fair)
Of a cube and a square,
And its name will most surely astound.

— John Gregory & Dale Seymour
Limerick Number Puzzles (Creative Publications, 1978)

• Sue VanHattum tells how she began reasoning through a problem in Tin Ceilings, Triangles, and Loving Math: “Coming up with a formula for $n \times n$ squares is a hard problem (which I’m not done with yet). But just looking for different size triangles, and maybe coloring some in, would be fun for a young kid, I think.”

[Photo by jimmiehomeschoolmom.]

Fermat solved a problem with ease,
That most of us find quite a tease.
His margin so small,
Left no room at all,
For a proof as concise as you please.

A challenge for many long ages
Had baffled the savants and sages.
Yet at last came the light:
Seems old Fermat was right–
To the margin add 200 pages.

— P. Chernoff

## BEST OF THE SPAM

[Photo by mrdodgy.]

There was a young fellow named Cole
Who ventured too near a black hole.
His dv by dt
Was quite wondrous to see
But now all that’s left is his soul.

— A. P. French

• There weren’t any decent spam this time, but I really like that picture, so I left the category in. The good news, for those of you who might consider hosting the carnival, is that I received about 1/3 the number of spam submissions as the last time I hosted. I hope that means the blog carnival website is cracking down on spammers.

## ALSO SHOWING…

MTaP is far from being the only math blog carnival in town. Check these out:

Math limericks are from Kayla’s Purlieu, Wikipedia, and Math NEXUS. I would like to link to the authors to give them credit, so if anyone knows a website associated with any of the names above, please tell me!

And that rounds up this edition of the Math Teachers at Play carnival. I hope you enjoyed the ride.

The next installment of our carnival will open on March 18 at Math Hombre. If you would like to contribute, please use this handy submission form. Posts must be relevant to students or teachers of preK-12 mathematics. Old posts are welcome, as long as they haven’t been published in past editions of this carnival.

Past posts and future hosts can be found on our blog carnival index page.

We need more volunteers!!! Classroom teachers, homeschoolers, unschoolers, or anyone who likes to play around with math (even if the only person you “teach” is yourself) — if you would like to take a turn hosting the Math Teachers at Play blog carnival, please speak up!

Claim your two free learning guide booklets, and be one of the first to hear about new books, revisions, and sales or other promotions.