This is true, but before you can freewheel the pedals on or drive the pedals off, you have to remember the threading rule in order to either initially thread them or crack them loose. Besides, as a mnemonic it's backwards (to me) -- it would be easier to remember if you drive the wheel in order to drive the bike (when you need the pedals on), and freewheel if you don't want to drive the bike (when you want the pedals off), but unfortunately that's opposite of the way the mechanisms actually work.