Hitting a flop shot off a tight lie requires that you attack the ball with a steeper swing and open clubface so that the club gets under the ball and pops it up softly
Getting full mobility in your wrist extensor is important because it allows your wrists to move properly in the backswing so you do not have an open face at the top of your backswing
Teach kids that with irons you must hit down on the ball to make it go up because the ball gains backspin by rolling up the face