Each set in this series contains two or three tapes and a book. The books contains the lyrics and music to a wide variety of folk tunes from around the world, hymns, and Gregorian chants. The Gregorian chants are relatively difficult, but the other songs are fairly easy to sing. I didn't know many of the songs, but we have enjoyed learning them. Each set of a book and tapes is roughly aimed at different ages, but I am having no trouble using the 4th-6th grade set with my seventh grade daughter. The sets are 1st-3rd grades, 4th-6th grades, and 7th-8th grades. The number of tapes in each set is the same as the number of grades covered. I recommend this program.