Aug 31 2005
Division of Fractions
J.D. has a great post at MathandText which provides a different method of dealing with the problem of teaching division of fractions. I really like the idea of building on students’ previous knowledge of equivalent fractions and common denominators. After a lifetime of cross-multiplying, the idea of actually dividing when doing division of fractions just seems so foreign.
I don’t recall ever seeing it done this way, but it works great. It is the equivalent of cross-multiplication, or invert-and-multiply, but makes it much easier for students to visualize what it represents. I think this could also be a really good way to introduce invert-and-multiply and to explain how it works.
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What’s even more interesting about this is that I first heard about this method from a mathematics education magazine.
A teacher had written to the magazine to share an interesting method for dividing fractions that was shared by one of his/her students.
–J.D.