I always remind my students and sons of 3 magic words that will create wonders in your life as well as other..
PLEASE, SORRY & THANK YOU..
say PLEASE whenever you want to ask something from your teacher
Say SORRY if you come late to the class
Say THANK YOU if your teacher has done something for your favour..
kindly use these three words wherever you go...
p.s. you were not courteous enough.. :-(