31.1Start with the distinction between beat and subdivision

In 4/4:

1 2 3 4

Each beat might divide:

1 & 2 & 3 & 4 &

or triplet:

1-trip-let 2-trip-let...

Meter tells you where the large accents live.

Subdivision tells you how the space between beats is divided.

A transformation can change either one—or both.