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.
(Positive number, the red arrow moves to the right.)
• 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.
Subtracting a positive number, blue arrow moves to the left. Notice that you can slide over to numbers larger than the first number (but not off the page ).
d. DIFFERENCE: What is the difference? What happens if the second number is larger than the first number?
• Click on "Show Difference " to see it on the number line.
e. EQUATION: Write down the equation for the subtraction. (Remember when two numbers have opposite signs you subtract the smaller from the larger and put the sign of the larger number up front!)
• Click on Show Equation to check your answer.
• Click on Reset to start over.