Students will learn to solve proportions and find missing sides of similar figures using the scale factor. This lesson is best taught before the concept of cross multiplication is developed. Not only will the student learn the process of using a scale factor to find a missing value from a proportion, but they will also practice these skills in a timed game online. They will realize that the scale factor is sometimes not an integer, and some proportions are more difficult to solve. This lesson is a great precursor to the means and extremes property of proportions also known as cross multiplication.