## Monday, October 21, 2013

### Monday Math Literature Volume 15

If you are new to my Monday Math Literature posts, click here to start from the beginning. If you missed last week's post about my favorite candy math books it is a great one to check out!

Today I want to share with you 2 of my favorite books to use with students in grades 5-8.  When I first introduce decimal or fraction multiplication, there is a big idea that I also must introduce with it.  When students' experience with multiplication is limited to whole numbers, they are used to the product being bigger than either factor.  For several years they have been under the impression that multiplication always makes numbers bigger.  When we start talking about decimal and fraction multiplication, that idea needs to to change and needs to be addressed directly.

My favorite way to address this?

This is a book by Pam Calvert who also write the Princess Peepers series.  It is based on the story of Rumpelstiltskin and is a very funny look at what happens when a wild man runs around multiplying by fractions less than one.  Things keep disappearing and Rumpelstiltskin causes a great deal of havoc before he is stopped.  Once he is stopped they have to figure out how to use his multiplying stick to turn everything back to the way it was.  This leads to a great discussion about how multiplying by a fraction less than one makes the product smaller than one of the factors and how to undo fraction multiplication.

Much to my great delight, several years ago another book was written for this mini series.

In this story, Rumpelstiltskin returns along with his evil accomplice the witch.  He has a division stick and is going around the kingdom turning things into frogs and dividing by whole numbers and fractions.  When the witch gets her hands on the stick, she tries to divide by zero.  This is an AMAZING way to introduce kids not only to fraction division but also to the idea of division by zero being un-defined.

Some really BIG mathematical ideas can be addressed with these fun stories!

Click here to head to Volume 16 where I have reviewed some of my favorite Hershey's chocolate math books!

#### 1 comment:

1. Except this book is wrong: dividing by a fraction does not always result in "more" - it depends on what the two numbers are: if it is 1/4 ÷ 1/9, then the answer will be "more," but if it is 1/9 ÷ 1/4, then the answer will be less. The lesson should really be about smaller into larger and larger into smaller.....