Which activity is most appropriate for teaching the concept of harmony in a music lesson?

Singing a round in groups is an excellent way to teach the concept of harmony because it directly involves the interplay of different musical lines sung simultaneously. A round is a type of musical form where two or more groups of singers start the same melody but begin at different times, creating overlapping sound patterns. This activity allows students to experience how different voices harmonize with each other, fostering an understanding of how harmonies are built and how they interact.

In contrast, listening to a major scale primarily focuses on pitch and tonality rather than harmonious relationships between independent lines. Playing a rhythm on percussion instruments emphasizes rhythm and timing, which are essential elements of music but do not address harmony directly. Moving fast and slowly to musical recordings might help with aspects of tempo and expressiveness, but it does not engage students in harmonizing melodies. Therefore, singing a round most effectively demonstrates the concept of harmony in a practical and interactive way.