8 Units with Short Written Exercises to Maximize Limited Study Time by Melody Bober, Gayle Kowalchyk, and E. L. Lancaster. This course is designed for teens who want to further develop their skills in music theory but have limited time to study it. It includes eight units devoted to the following subject areas Â- rhythm, intervals, natural minor scales, minor key signatures, musical terms and symbols, augmented triads, naming triads and inversions, and i-iv-V7-i chord progressions in minor keys. Each unit contains a succinct introduction to the subject matter, short drills for five days of the week and extra credit examples with further challenges.