I have speculated that one reason the Upper Room was prepared for the Holy Ghost to fall was precisely BECAUSE there was such energy and expectation in the room.When I was in a music group three centuries ago, I would FAR rather play in a church that seated 40, but had 60...than in a church that had 300, but seated 3000. There is energy and excitement, it seems, when you get that many people into a smaller space.To talk quietly and hope people will move up? I'm afraid there are people who not only would come to Sunday School if the anti-Christ was teaching, but who really could care less what is being said. They are just those that think faithfulness is being there in body. There are several possible solutions that I have used in the past....1) A week before, mention that you'd like to have everyone start sitting together so we enjoy each other's company or some such. On the night of, mention it again (sometimes it is a good idea to couple this with Let's take a few moments to greet each other while we are making our way to this side--to the back--this corner, etc.).2) Before anyone arrives, place the lectern well toward the back of the church. Put a Bible on it so people know it's not there by accident. Thus, if there are 15 rows, you place your lectern in the aisle at, say, row 12. If someone insists on sitting on row 7, encourage them to group together with the others. If they don't want to, let them enjoy your back while you teach the others. Also, you can place the lectern in the MIDDLE of a row, which signals that you will be standing there (again, toward the back, since if you do it at the front, they may all be spread from here to yon). In the middle of the row can help people know where you want them to be.3) Go to a Sunday School room or the fellowship hall, etc. OR THE CHOIR! The smaller the group, the more intimate the setting needs to be, I think.