Division of fractions — The role of ratio


A 4th/5th grade teacher I am working with planned to introduce division of fractions and needed some ideas. I knew that a context would really help kids make sense of the operation so I nudged her towards the book Minilessons for Operations with Fractions, Decimals and Percents (Imm, Fosnot & Uttenbogaard, 2008). We found a good place to start and I offered to lead the first string.

After we discussed the word ratio, I set up a ratio table with # of cans of paint and portion (of wall painted).

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Beyond Skip Counting

This post comes to us from strings enthusiast and middle school teacher Marcelle Good, who works at School of the Future (Brooklyn, NY) and is a Math for America (MfA) Master Teacher.


My 6th graders love to skip count. If you were to ask them whether, for example, 6 was a factor of 96, many would be willing to skip count (by sixes) all the way to 96. Even if they don’t find this tedious and inefficient, I do. So I’ve been working this week on generating some faster strategies for finding factors of numbers — also known as divisibility rules. Continue reading “Beyond Skip Counting”

Developing Algebra

This string was developed by our colleague Bill Jacob, University of California, Santa Barbara, who is, among other things, an algebraist.  The post is written by our colleague Monica Mendoza, University of California, Santa Barbara who leads a summer algebra institute for teachers as part of her work at The Center for Mathematical Inquiry with Bill. Continue reading “Developing Algebra”

Division – Whole number by fraction

During the spring of the 2012-2013 school year Kara Imm and I were working with my 5th graders to help them visualize what it meant to divide a whole number by a rational number. The students were very quick to invert the fraction and multiply. They loved saying, “Flip and multiply.” Mind you, I had never uttered those words in the classroom. However, this class was very used to string work and representing their work through models.

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