I’m only 50 but I voted for the mix of range and playing lessons. Perhaps you could make groupings based on skill level? However, I think if you did an on course teaching you could make it work as a scramble-like format. Discuss the tee shot strategy for the hole. Then have them each hit their tee shots. You could just choose a spot, use one of their tee shots yet discuss strategies for the other two. The next hole you would take a tee shot that requires a different shot/strategy and so forth. The range would allow you to see where your students are and help you organize groups that seem compatible.