Warmups are an underrated part of rehearsal.
Part of the reason is that warmups are less interesting than musical pieces. We can fix that with more interesting warmups – patter songs, diction games, different scales.
But part of it is that those who are warming up don’t know how to think during warmups.
Give your ensemble things to think about – timbre, ensemble, tuning, diction – and challenge them to notice things.
Or give your ensemble warmup variations that encourage thought. A familiar scale warmup? Sing it in a mode – maybe Lydian or Mixolydian. Singing eighth notes? Make it dotted, swung, reverse dotted, triplets, quintuplets.
Above all, assert and reassert that the warmup isn’t a chance to let your brain rest before the work of rehearsal. It’s a chance to warmup your brain so it’s ready for rehearsal, too!