Sarah wrote lyrics to the chromatic scale to help her students identify and sing half steps. These minor second intervals can be very challenging when singing songs that are coming down the scale - in the major scale the half steps happen between 3-4 and 7-8, and this is where many people go a little flat coming down. This exercise can help musicians get really comfortable with half steps so that they are more aware of where the notes are supposed to sit, and how close together they feel in the voice. It's simple but effective:). You can also try it as a "round" (with two or more singers starting from the beginning but at different times, like a measure apart) to further develop the ear.