Tuesday, February 9, 2010

Cardboard Fractions

Another cardboard post today. Emily and I were talking
about quadrants for preschool, and I thought I'd make
her a cardboard circle cut into four to better illustrate
the concept. This got me thinking about other fractions,
and anyway, here is a cardboard puzzle we made today.

We started out with six squares of cardboard. Ours were
8" x 8" because that's what we got out of the cardboard
box we cut up.

We kept one of the squares for the base - and cut small
finger holes in it.

We cut circles out of the other five. I don't remember
the diameter - somewhere around 6.5".

The girls got to work on decorating their circles. The more
distinct each circle is from another, the easier the puzzle is
to put together. They decided to turn their circles into fruit
pies, pizzas and cookies.

Meanwhile, I glued the five squares together in a stack.
Then I enlarged the hole a little - by about 1/4" - so the
circles would fit inside more easily later.

This stack-of-squares was then glued onto the base,
and the circles themselves cut into equal segments
(yes, I used a protractor):

Jenna enjoyed just putting together the fractured circles
in layers in the base. But to take it a step higher, we
talked about equivalent fractions -

two eighths = one quarter;
four eighths = one half;

two sixths = one third etc.

and when we were done, all the pie and
pizza pieces went back in the base

to be dumped out (or poked out through
the finger holes) another day.


  1. Wow. Creative and smart. I wish I had your math skills, mine are not so good. I will have to keep this in mind for when my kids hit grade school.

  2. Lovely! I've been waiting to do this with the cardboard pizza from ages ago, but I really like your idea of having them all fit in the cut out circles for storage!

    A long time ago you offered me the title of Queen of Cardboard. I think it's your turn to wear the cardboard tiara and toilet paper sash ;)

  3. KM: I will wear the toilet paper sash with pride. Very beauty-peagant-esque. But I leave the cardboard tiara with you, for you are more worthy.

  4. As a math teacher this warms my heart! : ) I love it! So creative!

  5. One third fantastic, one third fun and one third genius!

  6. This is an awesome project! I was just looking at a Learning Resources fraction pizza in the store the other day (with no intention of spending $18 on it). It only came with three denominators, though: 2, 4 and 8. I think we'll be making one of your fraction pizzas around here very soon.

  7. I love this idea! I need to get an exacto knife - I'm always cutting cardboard with our kitchen knives and scissors, and neither option works very well...

  8. I love this, my kids would too. Must get busy!

  9. very good idea, my kid is just starting fractions, so this will help a lot.

    thanks for posting this!

  10. what, no fifths? :) great project, BTW.

  11. I love this idea. I'll be making these with the kids in my resource class. I have a premade pizza resource, but the learning is greater when the kids make their own!

  12. I knew there was a reason I was stockpiling Ikea boxes in the garage! My son will love this - pizza and maths! Two of his favourites. And there is an award for you on my blog. I'm sure you must have dozens of them but that's the price you pay for being Kreativ.

  13. I love this math, art, and recycling activity for little hands. Thanks for sharing!

  14. Ah, good. I'll send P over for you demonstrate Venn Diagrams and how to calculate the probability of a single event...in cardboard.

    Maybe I shouldn't tempt you (:

  15. I LOVE this idea and will be sharing it with my friends that teach upper grades! My littles in first grade will LOVE it as well! Thank you!

    Oh My Little Classity Class

  16. Great! Just made one for my children.


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