Which key has four sharps? What's the one with two flats? And which one has seven sharps? By using the circle of fifths, it's really easy to see that it is simply a pattern. Our song is meant to be a very basic introduction and will help your students understand how key signatures work.
The first verse explains that you add sharps to the key signature when you go clockwise around the circle. The second verse shows that when you go counterclockwise, you are adding flats. At the end of each verse, the singers shout out the names of the keys in order as each sharp or flat is added. (from Music K-8, Vol. 28, No. 4)