Sometimes it is our interpretation of the directions and sometimes it is the way it is stated. Did the instructor know that you "tear" your fabric or did she assume that you just cut? Would the directions have been okay if you cut?
When I give directions/model something, I try to start with, "this is how I do it (and why); why not try it and see if it works for you." Classes are for learning and trying a new strategy/method and then self evaluating what works for you.