competency- based mastery learning: a planned clinical experience for nursing students baghaei r [1] , mohammadpour y [2] *, habibzade h [3] , rasouli d [4] , khalilzadeh h [5] , jafarizadeh h [6] received: 2 may, 2011 accepted: 6 july, 2011 abstract background & aims: clinical education is one of the most important and crucial parts of nursing education. successful clinical education...