## Sunday, September 5, 2010

### How Many Groups of 10?

There are 132 flyers that need to be handed out to Extended Day classes. The flyers need to be organized in stacks of ten to make them easier to hand out. How many stacks of ten will there be? How many flyers will be left over?

When looking at a two digit number, it is easy for students to determine how many tens and ones are in the number. When working with a three-digit number, students have to understand a little more about place value. In working with 100, students first need to understand how many tens are in each group of 100 in order to solve. This can be a little abstract for students at first.

To help them understand how many groups of 10 are in 100, we bring out the place value blocks for a visual. Let's start by representing the number 132 with place value blocks.

It is important for students to understand how many groups of 10 are in 100. By using the place value blocks, students can count the groups of ten easily.

When students understand that 1 group of 100 is equal to 10 groups of 10, they are able to solve these problems easily. Student work may look something like the following:

In the strategy above, the student drew a representation of the place value block model to explain her thinking.

In the strategy above, the student used a modified open number line to keep track of the number of groups of tens and singles.

In the final sample above, the student wrote what she knew about the number of groups of ten in 132. These are just several student samples. There are many more ways students can solve and model their thinking for problems like these.