## On a Number Line

## Opening

# On a Number Line

Discuss the following with your classmates.

You can also use a horizontal or vertical number line to model subtraction of integers as taking away.

Just as with the balloon simulation:

- Subtracting a positive number (heat) means moving in a negative direction (down or to the left).
- Subtracting a negative number (weight) means moving in a positive direction (up or to the right).