Definition: A fraction is simplified if the numerator and denominator have no common factors.
Simplify
1a) The square on the left illustrates (portion of the square shaded in blue).
1b) Find the GCD(9,15). Simplify . Drag the purple sliders to illustrate this fraction in simplest form.
1c) Use the handle (red point) to drag the purple square on top of the blue square. Do the shaded portions match? If so, you have correctly simplified .

Simplify
2a) Drag the blue sliders to illustrate the fraction .
2b) Find the GCD(5,20). Simplify . Drag the purple sliders to illustrate this fraction in simplest form.
2c) Use the handle to drag the purple square on top of the blue square. Do the shaded portions match?
Simplify
Move the purple square back to its starting position or click on reset.
3a) Drag the blue sliders to illustrate the fraction
3b) Find the GCD(4,16). Simplify . Drag the purple sliders to show two different equivalent fractions on the purple square.
3c) Use the handle to check both answers. Do the shaded portions match in both cases?
Simplify
Move the purple square back to its starting position or click on reset.
4a) Drag the blue sliders to illustrate the fraction
4b) Find the GCD(3,8). Can you simplify ?
How to simplify a fraction:
Click and drag the blue sliders on the left to the numerator and denominator of the (non-simplified) fraction you are given.
Find the GCD (greatest common divisor (factor) of this numerator and denominator. If the GCD is 1, you are done. If the GCD is bigger than 1, first divide the numerator by the GCD - the result is the "new" numerator. Second, divide the denominator by the GCD - the result is the "new" denominator.
Click and drag the purple sliders on the right to the new numerator and new denominator.
Finally, click and drag the handle (the big red point) to see if the sections match up.