Gear ratio can be found using the number of gear teeth or the comparison of rotations between the input gear and the output gear. [b][color=#0000FF]output gear # of teeth[/color]:[color=#FF0000]input gear # of teeth[/color][/b] [i]OR[/i] [b][color=#FF0000]input gear # of rotations[/color]:[color=#0000FF]output gear # of rotations[/color][/b] [b]Directions:[/b] Select the Play button in the lower left-hand corner to begin. Then, adjust the input gear # of teeth to see how the input gear size impacts the gear ratio.