What is a group piano lab?
In a "group piano lab,” students are at individual digital pianos with headphones. The instructor can monitor and interact with students individually or in groups.
Teaching the class as a group does not mean that the teacher never interacts with students. The teacher can walk around and observe students practice assignments, and make appropriate individual adjustments to posture, fingering, etc.
The teacher monitors and interacts with students through a kind of audio mixer (a "teacher controller unit" or "conferencing system") that is patched to the audio of each student’s pianos.