Thursday, July 9, 2009

Math Teachers at Play #11

(by L. Marie)

There's a whole bunch here. Get comfy, settle in, and enjoy!

What's Special About This Number? says the Maoris used base 11, 112 = 30 + 31 + 32 + 33 + 34, 113 = 32 + 192 + 312, and 11 x 11 = 65 + 56 (palindromic equality). And of course Wolfram Alpha (WA) has something to say about 11, too.

For this issue of Math Teachers at Play, we have games, geometry, arithmetic, logic, and some test prep.


Dana, at School for Us, brings us Score 21.

Clemencia Rosado, at Storytime and more, brings us M for Math Games.

Mike, from Walking Randomly, asks "Can anyone think of interesting extensions or variations to this system of wheels?" His Wheels on Wheels on Wheels is a spirograph extravaganza. (And here's another at Learning in Mathland.)

I've seen a lot of What Can You Do With This? posts all over the mathblogosphere. (Does that make it a meme yet?) Ryan, over the water at Maths at SBHS, brings us another What can you do with this? It's a visual illusion done with perspective and enlargement. Very cool.

And here's one from Watch Math on Slopes of Perpendicular Lines.

John Cook, from The Endeavor, brings you
Three rules of thumb. I've converted feet to miles, but never seconds to nanocenturies!

Tony, at This Young Economist, brings us
30-20-10 Pricing.
How much do you really get off when you get a 30% discount, and another 20% discount, and another 10% discount? Not as much as you might expect...

Maria Miller,
at Homeschool Math Blog,
brings us Dividing decimals.

Kendra, at Pumpkin Patch, also joins us from far away to give us a living math lesson using dominoes.

Denise, at
Let's play math!, brings us Solving Complex Story Problems II. She says, "Diagrams make it easy to model a multi-step word problem. When I was in school, we wouldn't have seen this sort of problem until algebra, but with these models, a 5th-grader can solve it." I've been hearing a lot about Singapore's bar diagrams. I'm looking forward to trying them out with some kids.

Misty, at Homeschool Bytes, says, "
Make math interesting by mixing regular household items with math concepts, like a handful of candy, two circles, and the concept of venn diagrams." See her post on Venn Diagrams.

jd, over at
JD2718, presents 5 logic puzzles. I think logic puzzles are my favorite mathy pastime. Thanks for some doozies!

Test Prep
Mr. D, at I Want to Teach Forever, has a question for us at the end of his post on 3 Ideas to Prepare Students for College Placement Exams. Can anyone help him find an answer?

And I thought I'd throw in one last bit. A few weeks ago I wrote a post about math and mountain climbing, and just now found out about this lovely post about math being like trees.

[Next time I host, I'll try to add a bit more spice. I've put this together in the middle of a marvelous week-long institute on running math circles, put on at Notre Dame by the folks from the Boston area
Math Circle.
That concludes this edition. Submit your blog article to the next edition of math teachers at play using the carnival submission form. Past posts and future hosts can be found on our blog carnival index page. Technorati tags: , .]


  1. Terrible formatting! I promise to do the next one in a better editor than blogger's.

  2. #11, huh? Where have I been? Better late than never...

    Thanks for the links. My reader just got a little fatter. Can't wait to hear all about the Math Circle workshop!

  3. The formatting did give you a bit of trouble, but the content looks great! I started browsing the articles yesterday, but didn't get very far before real life dragged me away from the computer. It looks like there's enough fun here to keep my free time filled for at least a week. Of to read another one...

  4. great work; the halfhour i've just devoted
    to clicking on the links here won't be the last.

    "formatting" never stops being a problem for me
    (even though i've agreed with myself that mostly
    if i can i'll let it be somebody *else*'s problem).
    trouble enough getting the letters and punctuation
    the way i want 'em...

    so now of course we're all eagerly awaiting
    the hopefully-inevitable "mathcircles" post...

  5. I get back home to California on Saturday, and I'll try to write something up (about the math circle institute) as soon after as possible. I had a blast, learned a lot, and feel closer to being ready to lead my own math circles.

    I'm actually looking forward to looking all those links over a second time once I get home.

  6. Hmmm ... not sure where to put this comment!

    Here's one from my 6-year old son Jordi - "Daddy how many ants in a pound of ants?"

    I then just had to turn it into how much does the entire human race weigh, and how big a volume does it take up? Pretty powerful lesson at the end.

    Take the challenge at Blog on the Universe:

    Jeff Goldstein, Center Director, NCESSE

  7. Hi Jeff, Thanks for dropping by and adding your comment. I guess it would fit best on my post about my son's question 'What is 500?', here. But it's fine here.

    I visited your blog, and added it to my list on google reader. Maybe I missed it, but I don't think you mentioned that all the ants in the world weigh more than all the people in the world - I like knowing that...


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