Signed Numbers: Colored Counters in a “Sea of Zeros”

The “colored counter” method is an old tried-and-true method for teaching the concept of adding signed numbers.  However, to show subtraction with the colored counter method has always seemed painful to me … that is, until I altered the method slightly.

Now all problems are demonstrated within a “Sea of Zeros” and when you need to take away counters, you can simply borrow from the infinite sea.  Voila!  Here’s a short video to demonstrate addition and subtraction of integers using the “Sea of Zeros” method.  You can print some Colored Counter Paper here.

Video: Colored Counters in a Sea of Zeros

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Calculus Tweetwars: The End

The Calculus Tweetwars: Act 3

We hope you’ve enjoyed the production of “The Calculus Tweetwars” and thanks to all that participated by interacting with the characters.
Also, check out our mention in the Chronicle of Higher Education Newton and Leibniz Duke it out on Twitter

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NYT Opinionator Series about Math

For a few months now, the NYT Opinionator Blog has been hosting a series of pieces that do a phenomenally good job of explaining mathematics in layman’s terms.

The latest article is about Calculus (with a promise of more to come): Change We Can Believe In is written by Steven Strogatz, an Applied Mathematician at Cornell University.

There are several other articles in this series, and if you haven’t been reading them, you really should go check them out.  Assign them.  Discuss them in your classes.

Given the discussions we’ve been having about teaching Series and Series approximations lately on Facebook, Twitter, and LinkedIn, I wonder if he’d consider writing an article explaining “Why Series?” to students.

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Carnival of Math: Mindmap Edition

Okay, okay … the Carnival of Math is late.  Sorry Mike!

Being something of a nonconformist, I thought I’d try something completely different!  This month, the Carnival of Math is in the form of an Interactive Mindmap.  So you’ve never used a mindmap?  Watch the quick tutorial (no sound).


Also, I’ve just thrown in my favorite posts from various math blogs that I read, so you may be surprised to see your own post in here!

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Community Site for Algebra Activities


I rarely talk about the books I’ve written on this blog, but the Community Site for my new book, Algebra Activities,  just launched and I think it’s pretty cool.  Also, I now have an author page.  Yay!

The basic philosophy for the book is to provide easy-to-use classroom activities to instructors so that they can easily replace lecturing time with more active learning.  The book also provides instruction tips and lesson plans so that any algebra instructor, especially new ones, can have a “mentor” to guide them and help them reflect on how students learn.

If you go to the Samples section of the Community Site, you can print and use some of the activities from the book in your classes.  You can also see some of the fantastic new algebra cartoons that were commissioned as part of this project.

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