Friday, April 27, 2012

A Useful and Beautiful Division

Me: Oh no!!  Four sets of Cuisenaire rods are all jumbled up!  I've got to get them sorted out before the next Math in Your Feet Family Night!  Do you think you could help me? 

Kid: How should we start? 

Me: I've set out four bags, one for each set of rods.  We need to divide up the rods equally so there is one full set in each bag.


Kid: (Finding all the orange rods.)

Me: "How many orange rods are there all together?"

Kid: "Twenty one."

Me: "How many orange rods go in each pile?"

Kid: (Starting with four in each group, then adding one more to each, one remains.)

Me: So, five in each group, with a remainder of one?

Kid: Look, Mama.  Four times five is twenty.  I knew that.

Yeah, I know.  I know that addition, subtraction, multiplication and division are steadily working their way into her consciousness and her skill bank, and all of this primarily by delving deeply into doubles, halves and evens.  I'm not kidding when I say that doubles/halves/even-ness comes up practically every day, one way or another.  I think it's a great way for a six year old to explore and learn about numbers, geometry, and the meaning of math.  There's actually something quite comforting in our daily discoveries of balance and symmetry whether in number play, through observations of our physical environment, or in the things we create with our own hands (the attributes matching game, for example, or our recent exploration of circles). 

I also know this kind of sorting activity is pretty basic, but having lots and lots of experience with operations in as many different contexts as possible is always useful.  In this case it was extra useful 'cause I didn't have to do this chore myself and I was able to work in some math inquiry -- sorting, classifying, measurement, division and a chance to get reacquainted with the rods -- all at the same time!   

1 comment:

  1. There's something deeply honest about the way the kid handled the 21 orange rods: starting with four in each bag, then adding one more to each, and letting the single leftover rod sit there as the remainder — that's division with remainders learned by the hands, not by a rule. And her triumphant "Four times five is twenty. I knew that" shows how division and multiplication check each other in her mind already. I also love your closing note that the same activity covered sorting, classifying, measurement, and getting reacquainted with the rods all at once; that's the efficiency of real contexts over worksheets. Full disclosure: I run the free tool site factorcalculator.org, where we spend a lot of time on how division leaves remainders behind. This post is a beautiful reminder that a useful chore makes the best math lesson.

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