Work Long/short, short/long patterns. For scales: VERY SLOWLY at first--play long, short, long, short, long, short, long, short up the scale several times. Then play short, long, short, long etc. up the scale several times. Then slowly play up the scale in equal note lengths. THEN same process down the scale. Increase tempo slightly as students master slower tempos.

This also works for any group of 2/4 notes (eighths, sixteenths) and obviously play only forward. Add the note that follows the 2nd or 4th and play long, short, long several times then short, long, short.