Charlotte Mason taught foreign language songs even before she started teaching solfa. Children of all ages can join in singing these songs together.
A great first German song to learn is sung to our traditional American happy birthday song. After you’ve mastered it, you can start to learn some longer German children’s songs. Each song below includes a video, written-out lyrics, a rough translation, and musical notation (where available).
The YouTube Channel Sing mit mir – Kinderlieder is a great resource. It has more songs than any other resource I’ve seen. The recordings are high quality and it is highly recommended. CDs are available (see below).