# ZeroSum Ruler (home)

## Blogging on math education and other related things

### Is Quirky a scam?November 18, 2010

Filed under: invention — ZeroSum Ruler @ 6:13 pm
Tags: , , ,

I paid my \$10.

I wrote all about the ZeroSum Ruler.

I submitted a picture, wrote my bio, wrote all about the ruler, and…..

Nothing.

No really, what is “Quirky”??

Still, I did manage to see that five people, probably unemployed and bored, decided to click on my product number to see what it was.  Here are their comments and my replies:

Becky Blatchford:

“I like this. If it is inexpensive enough say under \$10 I’d bet moms would buy this up!”

Me:

“Thanks Becky.  Hopefully they will when more people find out about it.”

socrtwo:

“Interesting and simple.”

Me:

“Thanks scortwo”

Michael Kloeckner:

“I love it, I cannot believe this is not out there somewhere”

Me:

“Thank you Michael. Now only to find a venture capitalist to back production and marketing!”

Dave McKey:

“I agree with Aaron. no need to fold the ruler.  good luck!”

Me:

“Thanks Dave.  I’ll think about the fold.”

Aaron Dale:

“I watched the video on your website and the only question I have is, why fold the ruler? Just make the ruler so it has negative numbers along one edge and positive along the other edge. But if a kid can use a tool to combine negative and positive numbers, they should use a calculator. It would be best for the kid to understand why they get the answer they get instead of counting the difference on the ruler. It seems like cheating.”

Me:

“I see what you’re saying about the folding.  it would be a lot easier to make without the fold.  The reason I made it fold was so that it starts out looking like the normal numberline the kids use in school.  The folding then shows the relationship between negatives and positives.  When a kid tells me -22 + 5 = -27, there’s a problem.  When this kid is in 11th grade, there’s a bigger problem.  When this kid is not just one kid but many, we’ve got a huge problem.  My thesis results are in and the ruler caused students to make 1/2 the mistakes as before the ruler.  True, data isnt’ everything, but I never thought it woule make such a difference. ”

So what is Quirky?  Can I build a website, undercut Quirky by charging anyone with an idea \$8 to write all about it only to have it disappear into a “relist” button one week later?  I mean, everyone has an idea, most everyone has \$8, this is the best scam going, right?

Am I missing something?

### Webpage blocked! [possibly]May 25, 2010

I found a great video at http://adgonzalezmath.wordpress.com/ in the “February 2010 archives” that lead to what could [possibly] be the greatest collection of math videos on all of the interweb superhighway: http://justmathtutoring.com/  I say “possibly” because, like many things that could be useful to students, the site is blocked here at school!

So I’ll check it out at home.  My bet is, based on the video I saw on adgonzalezmath’s page, the videos are going to be nice.  So if you know how to save videos from the internet onto your computer, I’d love to hear from you.  I know of one site that may [possibly] do this, but it’s blocked here.  Though even if it weren’t, I’d have nothing to upload!

### calculators KILL negatives! (uh, raised to even exponents, that is:)May 17, 2010

What’s negative 2 to the fourth power?  16?  -16?  If you put “-2^4″ into the TI-83, you get -16.  But we know that (-2)(-2) = 4 and (-2)(-2) = 4, and (4)(4) = 16.  So why does the calculator give us -16?

This post is no doubt for the high schooler and not for someone addicted to the )( buttons on the calculator like I am.  I parenthesize.  It comes from a fear that something will go negative that should be positive.  I have reminded my students more times than I can count to parenthesize, so many times, in fact, that I am more than sure that most tune me out as soon as they hear the first syllable.  But still the negative raised to an even number sneaks past the best of ‘em.

The evil negative base reared its ugly head again today when I graded papers on the geometric sequence an = a1 • r^(n-1) where:

an = the value of the nth term

a1 = first term’s value

r = ratio of change (ie “doubling” would be 2)

n = the terms placement (ie: 5th term would be n = 5)

“Find a7 if a1 = 5 and r = -2.”  The answer I or course got more than the correct answer was ” -320″.  What should the answer be?  “320″.  The problem should be written out first as: 5(-2)^(7-1) to make the process clear.

At least no one gave -1,000,000 as an answer.  There’s still hope!

### So, how much do I owe you?April 19, 2010

You friend borrows \$22 from you.  He pays you back \$15 the next day.  How much does he still owe you?  Asked this way, it’s obvious he owes you \$7.  But give a kid the problem -22 + 15, and the answer mysteriously becomes, well, mysterious.

WHY?

My students can certainly tell me how much I would still owe if I borrowed \$22 and paid just \$15 back. Like us, they’d probably count up from 15 to get to 22. But give a student the problem “-22 + 15″, and all bets are off.

For this number sentence, we are taught in school to find “-22″ on a number line and count to the right 15 spaces to find the number we land on. But this is not what we do in real life to find out how much someone still owes. There is a huge disconnect here.  In real life, we count up from 15 to 22, keeping a tally on our fingers of how many numbers we pass by.  We would never count up 15 from -22 to find how much someone owes us!  It’s no wonder students have difficulty with negative numbers with the way we are taught!

To plug my product, the ZeroSum ruler allows a student to count the spaces from 15 to -22 by folding the ruler in half at the pivot and counting from 15 to +22. When the positives are aligned with their negatives, they’re essentially finding the difference between the absolute values of -22 and 15.  This is the way we think and therefore a more natural way to learn.