If we multiply both the numerator and the denominator by the same (non-zero) number, the resulting fraction will be equivalent to the original fraction, for example . Sometimes students think that the same will be true for adding and subtracting. This applet helps to clear up some misunderstandings. The bottom part of the screen is the reference area. Here we enter a new proper fraction and see it as a part of a unit square. The top part is for experimenting with the fraction.

Click on the Multiply button. This will bring an input box and a operation button.

Enter a number and click the multiplication sign x . Repeat the same in the numerator.

Drag the Compare the Fractions slider to compare the original with the new fraction.

Click on Add button to experiment adding the same number to the numerator and the denominator.

Repeat with multiplying/adding several numbers in the top part of the applet, and with different fractions (lower part of the applet).