Mixed Numbers: The Various Operations

The theme of my classroom as of late has been hard work.  Seriously.  My kids have been impressing me one assignment after another....and this is just the latest one to have me thinking, "Wow, that was a rather difficult thing I asked them to do, and they did it!"

So, what did we do this time?  We learned how to add, subtract, and multiply mixed numbers.

One of the new things that I found myself teaching this year in greater depth than I ever had in the past was operations with mixed numbers. We had talked about it in past years, but I really never concentrated on it.  But when I saw the released questions when we were practicing for our new computerized state test, I actually had a mild panic attack.

Mixed numbers are just hard to deal with.  They have rules, but the rules seem to be just *slightly* different than regular fractions and regular whole numbers.  They are just different enough to make kids (and their 5th grade teachers) shutter.  Which is probably why I never really went full throttle on them before.  But now, there simply is no choice.  The kids have to be able to manipulate them.

So, over the course of a few weeks, we set about learning the different rules, algorithms, etc, associated with the three big operations (we don't need to work with division in 5th, so I am leaving that to the 6th grade teacher.)

Once I was sure the kids had the basic idea of all three, with lots of regular old practice, I broke out some simple task cards I made (you can get them for free here...the answer key is coming) which asked the kids to work on all three of the operations in more of a rigorous way.  Not simple problems, but problems masked around words. And, once again, the kids LOVED the task cards.  Seriously, I am still stumped by just how much kids like task cards, but they do, so I will keep giving the cards to them!



Next, I wanted the kids to put some of the pencil and paper knowledge to actual use, so I had them put a one inch border around a 12" x 12" piece of paper.  Then, I passed out some rectangles of construction paper cut into various sizes.  They used these as stencils and filled the inside space completely.

Then, the kids measured each of the sides.  This worked out well using inches because all of the sides measured to half inches or quarters or eighths.  Mixed numbers in a snap!

I then asked the kids to find the perimeter of each rectangle (forcing them to add mixed numbers), find the area (where they multiplied mixed numbers), and subtract the length from the width (subtracting).  The kids had to write all of their work inside each rectangle.

Seems easy enough, but this really proved to be quite the challenge for the kids!  Who knew!

I then put them all together "quilt" style.

So there you have it.  Two ways to get the kids practicing how to manipulate mixed numbers.  What have you done to work with mixed numbers?