Monday, May 18, 2015

Math Monday -- Pans of Brownies



It's Math Monday! 
for the Math Monday link up!


Dividing whole numbers by unit fractions and unit fractions by whole numbers are 5th grade standards.  (CCSS.MATH.CONTENT.5.NF.B.7)

I've never taught division of fractions, but when you are struggling to understand something yourself, you often do a better job explaining it to someone else.

In my classroom, dividing fractions is all about pans of brownies. 

If you have four pans of brownies and you want to divide them each into fourths, how many fourths will you have?

4 ÷ 1/4 = 16

You will have sixteen one-fourth-sized pieces to share with your friends.

But what if you you share 15 of those one-fourth-sized pieces and realize you forgot to share with 4 other friends? 

If you chop a one-fourth-sized piece into four pieces, what size of piece will each of those friends get?

1/4 ÷ 4 = 1/16

They will get a tiny little piece, but at least you didn't completely forget them!

Creative Commons photo from Wikimedia Commons


3 comments:

  1. Happy Monday!
    On Friday, I found out that I'll be moving from third to fourth grade next year. I thought at some point you'd mentioned a book title on developing a Math Workshop approach. I'm hoping you might be able to help me with the title and author.
    Thanks in advance!
    miss moyer

    ReplyDelete
    Replies
    1. Minds on Mathematics by Wendy Ward Hoffer is a great upper elementary book.
      Math Exchanges by Kassia Omohundro Wedekind is a great K-3 math workshop book.
      And here is a fabulous online resource:
      http://dublinmathworkshop.weebly.com/

      Delete
  2. Mary Lee,

    This sentence is so true, there's no better way to figure something out than by teaching it to others.

    I've never taught division of fractions, but when you are struggling to understand something yourself, you often do a better job explaining it to someone else.

    Also, how yummy to talk about brownies. I love how you took the problem further than everyone getting a fair share and while the last few students get much smaller portions, they still get some.

    ReplyDelete

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