I’m afraid this is only going to touch on the surface of a deep topic. We won’t even get as far as the technical details of chair type and placement today… just hit on a few theoretical points. Let’s see how much I can get out of one scanty semester’s worth of sociology, which I don’t plan to use at all, and the motto, “Most things can be reduced to geometry if you try hard enough.”
Your situation is a Sunday School class, pre-lesson. Said Sunday School class does not have an extremely high population value, but it is not extremely low either. (I.e. more than just you and your leader.) Your desired result for the combination of situation and population value is a room of happily talking people. How do you arrange this via the chair setup?
Your first thought is a circle of chairs. Just remember that 6 or 7 people (who know each other tolerably well) is the maximum number for a cohesive group. Any more than that, and your ratio of happy talking value to population value plummets. (Unless you are blessed with a high extrovert per head value) You will get either silence or a few scattered hushed chats.
Arrange the chairs in rows and you may not have everyone talking to everyone all the time, but you will have several free conversations going on, which easily provides you with a room of happily talking people. Since these conversations are not entirely isolated, every once in a while, you will attain the ultimate triumph – some topic will leak out of a group into the rest of the room and pull everyone into a conversation.
It’s all about geometry. And the moral of this geometry lesson is: Lines trump circles!