a/b = (n*a)/(n*b)
Pretty abstract stuff for a fourth grader! But with this simple and elegant activity, kids can visualize how multiplying the numerator and the denominator by the same number will create an equivalent fraction.
Just have the students use vertical lines to create and shade the first fraction listed. Then, have them use HORIZONTAL lines to create the equivalent fraction. You'll be able to explain, quickly and easily, how to make equivalent fractions!