Happy Thanksgiving!

Thanksgiving at the Trolls

Give thanks to the Lord, for He is good;
His love endures forever.
Let the redeemed of the Lord say this —
those He redeemed from the hand of the foe,
those He gathered from the lands,
frome east and west, from north and south.

Whoever is wise, let him heed these things
and consider the great love of the Lord.

— Psalm 107:1-3 and 43

[Feature photo above by Martha_chapa95 (CC BY 2.0) via Flickr. Quotation from Holy Bible, New International Version, (c)1973, 1978, 1984 by the International Bible Society, used by permission of Zondervan Bible Publishers.]

Pondering Large Numbers

[Feature photo above by Paolo Camera (CC BY 2.0) via Flickr.]

Half of our students were missing from this month’s homeschool teen math circle, but I challenged the three who did show up to wrap their brains around some large numbers. Human intuition serves us well for the numbers we normally deal with from day to day, but it has a hard time with numbers outside our experience. We did a simple yet fascinating activity.

First, draw a line across a page of your notebook. Label one end of the line $20 (the amount of money I had in my purse), and mark the other end as $1 trillion (rough estimate of the US government’s yearly overspending, the annual deficit):


  • Where on that line do you think $1 million would be?

Go ahead, try it! The activity has a much greater impact when you really do it, rather than just reading. Don’t try to over-think this, just mark wherever it feels right to you.

The kids were NOT eager to commit themselves, but I waited in silence until everyone made a mark.

  • Okay, now, where do you think $1 billion would be?

This was a bit easier. Once they had committed to a place for a million, they went about that much farther down the line to mark a billion.

Continue reading Pondering Large Numbers

Math Teachers at Play #68 via Mathematical Mischief

CERDEC Math and Science Summer Camp, 2013

[Photo by U.S. Army RDECOM CERDEC (CC BY 2.0) via Flickr.]

The Math Teachers at Play blog carnival is a monthly blogging round-up shared at a different blog each month, featuring posts from parents, teachers, homeschoolers, and students — anyone who is interested in playing around with school-level (preschool to pre-college) or recreational math.

This month’s edition is ready for your browsing pleasure:


Good morning, everybody! This month’s edition of Math Teachers at Play is edition number 68. Also known as edition number {{2}^{2}}({{2}^{4}+1}). Or edition 31+37 or edition 7+61…. Alrighty, so… did you know that 68 is a happy number? That’s right, it’s not unhappy, it quite likes the way it is.

There’s certain numbers that exist that are ‘happy’ numbers. This is because the sum of the square of their digits is equal to 1. So, for 68, the two digits are 6 and 8. Adding the squares, we’re given {{6}^{2}}+{{8}^{2}}, which equates to 100. Adding the square of each of the digits makes 1, which is happy!

  • Can you find some more happy numbers?
    I’ll give you a hint – the first one is 1.

Anyway, back to the carnival. This carnival features 11 articles – smaller than last time, but still just as awesome and creative as ever….

Click here to go read the whole carnival: 11 great ideas for teaching math!
[By the way, did you notice? 11 is a happy number, too.]

You may also enjoy:

Every Day Is Math Day

Happy 11-12-13

Happy 11/12/13, otherwise known as “tenty-one, tenty-two, tenty-three.”

Do your young children have trouble counting in the teens? Try making up Funny Numbers to help them! It’s a great habit to develop, because Funny Numbers will come in handy as mental math tools throughout their school math career.

If you’d like to make your own Happy Math Day post, check out the instructions here: Every Day Is Mathematics Day. And please share a link in the comments section below — I’d love to see what math holiday you invent!

Update: The numbers 11, 12, and 13 form an arithmetic progression. If that sounds too scary for your kids, check out Patrick’s bedtime math discussion Making Progress, Arithmetically.

Algebra for (Almost) Any Age


Fawn Nguyen’s Visual Patterns website just keeps getting better and better. Check it out:

In addition to the 115 puzzle patterns (as of this writing), the site features a Gallery page of patterns submitted by students. And under the “Teachers” tab, Fawn shares a form to guide students in thinking their way through to the algebraic formula for a pattern.

How can you use these patterns to develop algebraic thinking with younger students? Mike Lawler and sons demonstrate Pattern #1 in the YouTube video below.

A Good Problem Requires Dreaming Time


A good problem should be more than a mere exercise; it should be challenging and not too easily solved by the student, and it should require some “dreaming” time.

— Howard Eves

CREDITS: Today’s quote is from Howard Eves, An Introduction to the History of Mathematics. Background photo courtesy of Brenda Clarke (CC BY 2.0) via flickr.