1 . Make sure that nobody is watching.Look around and check out the faculty around you; make sure they aren't interested in what you are doing. However, realize that teachers see a LOT more than they let on...
2 . Find a way to look at your phone. Slip your hand into your pocket and pull it out under your desk. Hang your phone down near the ground so it looks like your picking something up, or put it in your pencil case/coat pocket and pretend to be looking for something.