I have been teaching and playing the violin for many years, all ages and standards. My philosophy is to teach everyone to the highest standard that they are able . I have a pupil with a missing index finger on his right hand...the index finger was used to replace his thumb. He was born with no thumb on his right hand and he also had some surgery on his left hand. He is left handed for writing. I had never taught anyone with any hand limitations so teaching this child was a very new and challenging experience and at first I suggested the trombone! Two years later and he is playing the grade 1 pieces! He is a perfectionist and has found his own way to bow straight but the bow buddy he uses causes a lack of flexibility in his wrist. The latter is nothing to do with the bow buddy, just the way it fits his hand.