# Centimeter Number Lines

Number lines are a great way to build number sense and to model operations. Centimeter rulers, centimeter number lines, and meter sticks can be paired with Base 10 Blocks and Cuisenaire Rods to model all kinds of math, including:

### Base 10 Blocks

- Simple place value activities with Tens and Ones
- Addition, especially useful for adding multiples of 10, illustrating associativity (grouping Tens and Ones in any order), etc.
- Subtraction in ways corresponding to addition
You can illustrate breaking apart, or decomposing, numbers easily with B10B.

At the left is 23 + 15 = 38.

Or, 20 + 10 + 3 + 5, or 23 + 10 + 5.

### Cuisenaire Rods

- FACT FAMILIES! These are the best possible way to model fact families for both addition/subtraction and multiplication/division
- Introducing multiplication as repeated addition, and, of course, division in the same way.

The picture at left modeling 6 times 4 with Cuisenaire Rods.

This also shows 24 divided by 4, as in *“How many fours fit into 24?”*

This is measurement, or “quotative,” division.

Here are some images of number lines longer than a standard ruler that you can insert into a document (several will fit on one page), print and copy. You can print the entire page, laminate it, and then cut the number lines out. Or, if you have time, cut the individual number lines out first, laminate them, and then trim the lamination to leave some border.

Always print a single sample page and measure the number line for accuracy. There are often small variations in the size of printed images depending on the software and printer being used. You want the length of your number lines to be exact!

There are 2 different sizes of number lines.

The top image is from a Word file that prints four 41-cm number lines to a page. If there are problems with the length, you can resize the image. To properly size the image on the page, lock the aspect ratio. Then set the length of the image to 16.75 inches. This may take some trial and error.

40 cm – fits on 17 by 11” paper, 4 to a page (Word)

Many school offices have a copier/printer that can handle this size paper.

The second is 56 cm long. You need a poster printer to use this size. This can be inserted into poster-making software like Canon Poster Artist.

This is actually a double image intended to be folded lengthwise, so one side is not numbered. Of course, you can choose not to use the blank side and have only a numbered line if you wish. The (double) image size as is is 22.42″ long and 4.45″ wide.

The 56-cm number line is my favorite, because it fits easily on a student desk, and yet the range of numbers is big enough to illustrate any operation and concept including most basic multiplication facts and addition/subtraction with regrouping. Meter sticks are difficult to use unless students are sitting at tables.