This blog is still alive, just in semi-hibernation.
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Wednesday, February 24, 2010

Wednesday Math, Vol. 110: A simple mnemonic for division and zero


You might remember from a math class ages ago that you can divide by zero. The problem is that a lot of students just hear "Zero... division... bad." It's perfectly okay to cut zero up into as many pieces as you like, but chopping a thing into zero pieces is problematic. This means another set of students will know that one way to have zero in a fraction is all right while the other way is bad, but they will forget which is which.

Christine Will, one of my fellow teachers at Laney, put this mnemonic up on the board during a talk and I think it's a good teaching tool.

11 comments:

Wormwood's Doxy said...

As I have a child who is just beginning to learn division, this is great--thanks!

susan s. said...

My brain hurts!! But I don't have to know this stuff, so I won't think about it any more. Clever mnemonic, though.

47th Problem of Euclid said...

No offense, but why do people feel no hesitation to admit to ignorance when it comes to math, but nobody admits to being ignorant of good hygiene? Just asking.

Matty Boy said...

Comparing ignorance of math to ignorance of proper healthy habits is a bit harsh, but I did a compare and contrast between people who don't get math and people who don't get poetry a few years back.

http://lotsasplainin.blogspot.com/2008/01/poets-are-to-mathematicians-as.html

susan s. said...

No offense, but I just know offense is intended when someone starts a comment with 'No offense.'

Matty Boy said...

I was being too even handed. I know 47th PoE personally, and I only know Susan as a commenter here, but I do think his comment crossed a line and anyone would be offended by it.

As a math person, I understand the frustration completely. For me, watching TV and seeing so-called "experts" on topics wheeled out who cannot do the simplest math is like reading an article with a few dozen misspellings. As a teacher, I also fully understand that students don't use math in their everyday lives and things they have learned fade away, not unlike my vocabulary in languages I learned in school like French and Italian.

That said, comparing lack of ease with math to lack of knowledge about personal hygiene is going too far.

susan s. said...

Matty Boy, I was not bothered by your remark. I have a fairly thick(and clean!) skin. I am, I confess, an old woman who has forgotten a lot, and I would never put myself out there as an expert on anything relating to math. I like to read your blog and sometimes make inappropriate remarks. Just ask the Padre! ;-)

Sridhar Chandrasekaran said...

Simply a superb mnemonic. In fact, this particular division rule confuses me and you have given a great mnemonic for it. thanks

Anonymous said...

I think a better analogy is that it is okay to claim ignorance of math but if someone claimed that they were illiterate, other people would be horrified.

Tonya Garcia said...

Such a clever idea! I printed this and posted it in my classroom on bright paper. I outlined the N/O in red and the O/K in green. Even my junior and seniors have trouble remembering this rule. I think this will help a lot. Thank you!

Matthew Hubbard said...

To Sonya and Sridar: Glad to be of assistance. The idea is not mine originally, but it is a good mnemonic and I'm glad to help spread it in any small way that I can.