A very typical vocal warmup is to sing scales up and down from a note. Then again from the next note up. And so on, so you're going up and down but slowly moving higher and higher (or sometimes lower and lower). Often they'll play a chord at the end of each scale up/down.
But what is actually being played here, typically? Would it be as simple as playing each major scale, moving the starting note up chromatically each run? Or staying in the same key but moving the starting note one degree each time?
I can find an example video if needed but I'm assuming any vocalist or pianist who works with singers knows exactly what I'm talking about.