OK, so I will admit it.  When I have 50-500 students in a class, I cannot watch all of them!  Does your front foot heel draw a line into your back mid arch?  It sounds like a TRAIN lyric from one of their hit songs  Hey, Soul Sister!  (BTW, Big YogaForce Fans...)  But, seriously, you DO need to align your body when doing all floor exercise or you can hurt yourself.