A study by the University of the Arts, London, suggests that learning a musical instrument at primary school can boost a child's confidence and learning in other areas.
(It was said to improve motivation and behaviour, because it is a social activity that engages the child's emotions and self expression, and it can improve the way a child collaborates without any competitive element. I'm not sure about the lack of competition, and anyone who's been laughed at for playing the wrong note in the school orchestra would agree with me.)