This week’s vocalize is the entire final phrase of the top line. It should all be sung in one breath, thus it’s a good exercise for breath control.
For this passage I suggest that you start at a fairly brisk pace so that your singers don’t have any trouble singing each and every note. If you find they’re having trouble with intonation either sing on solfege syllables or first work on smaller sections of the passage. The first two vocalizes in the series are essentially bitesize versions of the passage so you can start with those. If their intonation is good, gradually bring the tempo down until they aren’t able to sing all the notes in one breath. Then bring tempo back up again.
In addition to breath control you can work on dynamics: have one or more climaxes, have different dynamic levels (i.e. mostly loud, mostly soft, etc.), or have different dynamic ranges (i.e. very soft to very loud, medium loud to very loud, etc.).
The range is a little bit more than an octave, so feel free to go up the keyboard and back down a couple of times so that there’s been enough breath control practice.
And don’t forget resonance! The “e” in “Be” should be accompanied by a buzzing feeling in the face.