Dana Goldstein reviews the literature:
Something called "character education" is quite trendy in education reform right now. It's based on research from positive psychologists such as Martin Seligman and Christopher Peterson that suggests traits like "grit"--perseverance, goal-orientation, and long-term ambition--are more highly correlated with academic and workplace success than traditional measures of skill and talent such as IQ.
[W]e have no idea whatsoever whether traits like grittiness can be taught in school. To what extent are they taught at home? To what extent are they internal to a child's DNA? As Education Week reports, the largest to-date federal study of character education programs has found they lead to no discernible, long-term improvements in students' academic performance or behavior.