I’ve found that a sure-fire way of making a rehearsal interactive is to ask a quick question. First, it keeps the choristers on their toes. Second, they want to be the one with the right answer! But thirdly and most importantly, when they get the answer they OWN the lesson.
When anyone hears a question, whether they venture to answer is not the point. They consider it. And when they consider the question and receive the answer, then they’ll apply the concept more naturally and do it more consistently in the future.
So, no matter what the ages of your ‘students’, give them a pop-quiz. And watch how readily they respond to the point you’re trying to make. (Ex. “What is the operative word in this phrase?”)