Most days, my warm-ups began by asking the choir "Where's your A?". I was always curious about relative pitch and if it could be taught or trained. I think that answer is yes because by Halloween, even the least talented among us could sing an "A" - as they had memorized the pitch.
From there, I would say "Drop the octave" and everyone would sing an A major scale. "Where's your E?" "Bass II's sing the scale descending." "Where's your C?" "Where's your G?" "Alto II's sing the scale descending.: "Where's your Bb?" "Tenors and Basses, sing this falsetto with the Sopranos and Altos - do NOT drop that octave!" If you are familiar with the NJ All-State Chorus audition scales, you will see the pattern here covering every voice part in daily scale work.