The Number Line

a. SCALE: Set the scale of the number line that is:

• Type in a number >=1 and <=500.

• Then click on the **Set Scale** button.

**Remember:** arrow for first number starts from 0, arrow for second number starts from end of first arrow.

• Now click on Ready for First Number.

b. FIRST NUMBER: Click and drag the point on the red slider to the value of the first number.

• Now click on Ready for Second Number.

c. Second Number: Click and drag the point on the blue slider to the value of the second number.

We are subtracting so, if the value is positive the arrow shifts direction once so goes * left*; if negative, the arrow shifts direction twice so goes right.

d. OPERATION: What is the result?

• Click on "Show Result " to see it on the number line.

e. EQUATION: Write down the equation for the operation and then do the operation. Remember that subtracting a negative number is like adding a positive number.

• Click on Show Equation to check your answer.

Move the red slider to a positive number. (Notice the blue slider moves back so we don't go off the number line ). Now we are adding 2 positive numbers" - easy! Move the red slider to a negative number and say with words how you calculate the result of adding a negative and positive number.

• Click on **Reset** to start over.

LFS with idea for number line by Megan Yanes and for pseudo-slider by Zen Biker Maniac - Created with GeoGebra