Monday, 16 July 2012

Intro to fractions

Yesterday, when my daughter and I were making a Brownie in a Jar recipe for her friend's birthday, I let her take a go at reading the recipe.  There were fractions in it, and she wasn't sure how to read them, and she didn't really know what they were either.  But she was happy to know how to read "sugar" and "cup", and that there were chocolate chips in it and a party to head off to soon.

I felt like it was a missed opportunity.  Sure, kids in our school division don't start learning about fractions until grade 3.  But she's going to be seeing them every time that we make a recipe or measure something.  So, how could I help her understand what those numbers and lines meant, in a way she would understand?  I was laying awake last night pondering that.  It had to be quick, easy, short on long words like "numerator" and "denominator", and hands on.  Here's what I came up with.

First, we got a blank piece of paper.  I wrote down a couple of numbers that we saw in the recipe and asked her if she remembered them.  She did.  I asked her if she understood what they meant and she said she didn't.  So, I went to the classic pie example.  We talked about the bottom number first.  It told us how many pieces were going to be in the pie.  I drew a picture to illustrate the first fraction I wrote.  Then we talked about the top number.  It told us how many pieces we would get.  I coloured the pieces in on my drawing.  We went to the next fraction and I asked her to show me what the bottom number meant.  Then what the top number meant.  She got it quickly, and then cut the pies into many pieces and coloured them all, saying she wanted to share the pieces with her family.

So then we went back to the recipe.  I told her that instead of a pie, we would now use the measuring cups and see if it really worked.  We took a 1/4 cup and a liquid measuring cup.  I showed her the number on the 1/4 cup and asked her how many she thought we would need to fill the full 1 cup.  She told me 4.  And then we tried it out, just to check.  And sure enough, she was right!  We did the same thing using a 1/3 cup, and it worked again.

She doesn't know they were called fractions.  She didn't hear the words "numerator" and "denominator".  But she remembers that we did an experiment, and what the outcome was.  That's what will matter for today.

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