Fraction Multiplication

I had a small epiphany in my kitchen this afternoon, cutting copy paper into ever-smaller strips. I didn’t like the EveryDayMath “jumping” thing and I don’t want to just hand over the algorithm.

What does it mean when we say, “what is one third of one fourth?” What does that look like and how can we represent it? If I cut a strip off the bottom of a piece of copy paper, and call it My Whole, then cut another just as long, but cut it further into three pieces, these are thirds. Cutting another Whole into thirds, and then each of those pieces into four pieces, I end up with twelve pieces, and each of those is one Fourth of one Third. Playing and cutting, I can figure out the a/b of any other a/b, as long as I keep the b’s small so I don’t end up with 81 super-thin slivers of paper or whatever.

I want my students to know the “why” and “how”, not just a mechanical reflex. I want them to see these parts in their heads, fitting together and moving about.

About gblakney

Middle School Mathematics Teacher, passionate EdTech user who loves to experiment with new methods and tools in the classroom. Following the lead of Dan Meyer and Jo Boaler, I create a safe place for kids to discover the fun and beauty of maths. I use Number Talks and Groupwork to make maths accessible for all of my students. I enjoy Mathematics and I'm enthusiastic about teaching; the kids really respond to that.
This entry was posted in Ideas, Math Content, Planning and tagged , , . Bookmark the permalink.

I'm interested in what you think on this issue...

Please log in using one of these methods to post your comment: Logo

You are commenting using your account. Log Out / Change )

Twitter picture

You are commenting using your Twitter account. Log Out / Change )

Facebook photo

You are commenting using your Facebook account. Log Out / Change )

Google+ photo

You are commenting using your Google+ account. Log Out / Change )

Connecting to %s