This applet can be used to explore addition and subtraction of fractions. The applet provides a unit fraction bar and two additional fractions that can be controlled with the input boxes. The scale factors can be used to change denominators. If common denominator is not selected, Fraction 1's numerator and denominator are each multiplied by scale factor 1. Scale factor 2 works similarly for Fraction 2. If common denominator is selected, each fraction is converted to one with a common denominator. The scale factors allow the user to try and figure out the common denominator independently.

Example Problems:
Suppose Fraction 1 is 1/4 and Fraction 2 is 2/3.
1. What is the common denominator?
2. What value of scale factor 1 would convert 1/4 to an equivalent fraction with the common denominator?
3. What value of scale factor 2 would convert 2/3 to an equivalent fraction with the common denominator?
4. What is 1/4 + 2/3?
5. What is 2/3 - 1/4?