Here’s a great lesson plan that uses music theory to explain math set theory. Help your students identify sets and intersections of sets with this musical activity. Using the concept of key signatures, students will learn that scales are sets of notes. Students who have some knowledge of music will understand this easily, but they don’t need to have a musical background for this to be a worthwhile lesson. In fact, using music makes the concept of set theory much more concrete. This lesson plan is comprehensive, with links to resources that will help in instruction. Included with this lesson plan are downloadable worksheets and answer keys.