QUOTE(sarah-flute @ Oct 10 2006, 11:26 PM)

I think it's optional as long as scales are played rhythmically; probably depends which instrument. I always found playing in triplets helps me keep in the right place.
It's the piano. I think the 'blank' is because it is the only set of scales in 3 octaves, since the others are 2 or 4 octaves.

thanks for all your replies so far.