DORSETBOY:head up when teaching as it's easier to equalize and that's what you want your students to take esp care with!
Being able to control descent speed (buoyancy control) is what I think makes equalization easy to manage. If a student isn't over weighted and only becomes slightly neg at the surface (as apposed to dumping all they're air) a nice slow descent can be made without the need to to have fins pointed at the bottom causing the infamous OW mushroom cloud when the class gets within 15 ft of the bottom.