Friday, March 18, 2016

Homeschool Math: Rice Krispy Treat Fractions

Here's a super simple way to get some extra fractions enrichment into your kids' day:

Make anything that's round or square--pizza, cake, pie, quiche, or Rice Krispy treats. Nom!

You get bonus points, of course, if your selection is a treat.

Next you give your kid a big ole knife, and challenge her to cut her treat into specific fractions. Cut it in half. Take a half, and make fourths. Eighths. Can you make sixteenths?


With a Rice Krispy Treat, you can!


Put the pieces back together in various combinations and determine their fraction.

Find all the equivalent fractions. Calculate 1/2 of 1/2 of the Rice Krispy Treat. Copy that equation down onto paper, and take a picture of the Rice Krispy Treat piece to go with it. Give a kid 1/4 of the Rice Krispy Treat, then take away 1/2 of that--what does she have left?

Even if you're doing a rigorous math curriculum, as we are, casual, simple explorations like this are crucial to a kid's math understanding. Math needs to be conversational--a kid isn't going to "get" math if the only time she encounters it is in a textbook. Math needs to be practical--what kid DOESN'T understand the need to divide a treat perfectly equally? Giving her four pieces of a treat and telling her they need to be divided among three people is the sneakiest way to get her to an understanding of adding, subtracting, and equivalent fractions that I've ever found!

Most of all, though, math needs to be hands-on and sensorial, even for these "big" kids of the ripe old ages of nine and eleven, even with something as simple as composing and decomposing fractions at those ripe old ages. Pattern building is one of the cornerstones of intelligence, and in order to build a reliable mental conception of what fractions ARE, we need to see them in all shapes and sizes and combinations so that we can build that pattern. We need to see 1/4 not just in a textbook, but in pattern blocks, Base Ten blocks, apples, game boards, measuring cups, gas tanks, bottles of milk, pieces of pie, trips around the block, and so much more, all the time, as much as possible, as naturally as possible. If you can see what 1/2 of 1/4 looks like in your head, whether you're visualizing a Rice Krispy Treat or a glass of water or your Cuisenaire rods, then you're well able to understand the algorithm that lets you calculate it, which means that it's easier to memorize and it's easier to perform and it's easier to apply.

And down I step off of my soapbox, primarily because if I continue to rant on, I won't have enough time to make egg sandwiches and prep the school table for today's work before the kids wander in and start begging for just half an hour of screen time before we get started, AND I forgot to make a big batch of salt dough yesterday, so I need to do that right after I get the kids settled in with cursive and Books of the Day. AND if I want them to help me in the garden--and I do!--I need to get them through their school quickly so that I can pretend to Will like the gardening is the work that we have to get done before I can take her to the library.

However, if you've got more time to browse the internet than I do this morning, here are some of my other favorite activities for fraction enrichment:

  • edible chessboard: Fractions up to 1/64, and you can play chess and checkers on it!
  • fraction art: The fun part is making the art; recording the fractions of each color is not fun, but IS a great illustration of what fractions look like, especially if you've got more than one person doing the activity. 
  • spiraling decimals: This is a fun game, and it's tricky! Convert the decimal cards into fractions, of course, before you play.
  • Roll a Whole: When we play this one, we usually play up to something like five wholes, and then I have the kids draw their results.
  • fraction flags: You can use these, or homemade decorations and frosting, to record the fractions on your treat.

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