You think I'm kidding, but rearranging the seating has a HUGE effect on classroom management in my experience.
Changing up the classroom causes the students to try to figure out what is going on, and they get excited about the lesson. If you normally use tables in Seminary, set up without them. If you normally don't use tables -- set up one Sunday with them and do a drawing or note taking exercise. The break from routine really helps students get excited about lessons.
I gave a detailed lecture on this topic during the Teaching Saints Virtual Summit over at Leading Saints. The summit was free when it first broadcast, but it is well worth your money to pay for and watch the entire summit. I didn't/don't get paid for promoting Leading Saints and did the podcast for free. Running a podcast is expensive, and Kurt is doing amazing work over there. Check it out!