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Sunday, February 10, 2013

Numerators & Denominators

One of the hardest concepts about fractions for students to remember is the terminology of fractions. The most common question I get is "Which one is on top, the numerator or denominator?"

Why it's important to know the nomenclature of fractions isn't as critical as knowing what the numbers on the top (how many parts you have) and bottom (total same sized parts) represent. However, since it probably comes up on the test, students probably should learn it.

When the question is asked, my usual response is: "Denominator starts with the letter "d" and so does the word "down". The other one is the numerator since I can't think of a word for the top part that starts with "n".

So it was in a 4th grade class studying fractions that I asked: Does everyone know what the top and bottom parts of a fraction are called?

All (in sing/song voice): "denominator starts with "d" and so does the word "down". nominator starts with 'n' which looks like an an upside-down "u" that stands for "up".

Me: "Wow, that's pretty good! Where did you guys learn that from?"
Dude in front: "You taught us the first part last time you were here and our teacher liked it and came up with the second part".

I am totally going to steal that for the next time this topic comes up.

If you found this post searching for why they are called the denominator and numerator, Ask Dr. Math does a pretty good job of it.


The Bus Driver said...

Thats brilliant! i once had a class i was subbing for that i used a stopwatch.. every minute they wasted of my time by being loud while i was trying to give out directions, i would take away from their recess... their teacher liked it so much, that she adopted my method....

Alex T. Valencic said...

When I teach numerators and denominators, I teach the etymology of the latter. We look at the parts of the word and consider other words we know, such as "nom de plume" and "denomination" and how all three have the root "nom" which means "name." The denominator is the name of the parts of the whole. The numerator is the number of the parts.(Notice that both have the "num" root.) Most of my kids (at least 80%) accept this and it helps them remember. The number of parts on the top, the name of the parts on bottom.

I may use your trick to help those kids who are still struggling to get them to make sense!

Alex T. Valencic said...
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WeHelp2Learn said...

Thanks for sharing this tip. :) I will be using the Denominator D for Down and Numerator n is like an upside down "U" analogy for "Up!" I think this is so helpful. As a first year sub, this stuff really helps. When I was taking a class in college to "brush up" last year....I absolutely loved little helpers like acronyms or word games for remembering -- they are like *Gold*! I know I also loved a good story! :D (aesop's fables or old mid-west stories are great). --thanks

SunyDay76 said...

I have taught this by playing "Denominator" instead of limbo. The kids know it as limbo, which is just a made up name, so why not call it something else that will help them remember. They never forget. Once they were doing high jump in PE and they came back and told me that they were playing numerator!