This synchronization exercise is not new. I remember my Dad doing this with us in his church choir – must be about 45 years ago now.
For any song on which the choir is having difficulty locking in to a tempo, have each choir member rest a hand on the shoulder of the person beside them, and tap the beat as the song is sung.
Depending on the collective personality of the group this one can have them rolling in the aisles, annoyed or uncertain.
The script then calls for the director to say: “You’ve probably noticed by now how far off your neighbour’s rhythm is.” Almost everyone will have noticed that their neighbour has a completely different idea about where the beat is.
The good news is that all this says is that people weren’t really giving all of their attention to the beat.
Now try the same exercise with everyone’s eyes closed. The result is usually much better.
Sometimes it takes several times through with eyes closed before everybody understands that this is really important. When every singer realizes the amount of concentration needed, the synchronization will improve dramatically.