This lesson emphasizes music notating skills using “Mouse Mousie” from Lesson 1. In Lesson 3 we wrote the notes in the spaces of a 5-line staff. In this video, Heather will show how you can sing the song starting on a different pitch (or note). When we start on a different pitch, we have to write the notes in a different place (in this example, on the lines of a 5-line staff). This is called transposition or changing keys.