Most of the songs in Rise Up Singing (as well as our new book Rise Again) have lyrics and chords only. You have to learn the song from a Youtube video, from the Rise Up Singing teaching CDs, or from your friends.
Rounds, however, are challenging to sing with others even if you know the tune without having the music in front of you. Rounds, therefore, do include music. There are two chapters in Rise Up Singing with rounds - a chapter of secular rounds and another chapter called "Sacred Rounds & Chants".