I've written posts before about the importance of students accepting responsibility, rather than blaming other people for their mistakes. Of course, it's not just a good lesson for kids. It's one of the secrets of successful adults, too.
From comedian Chris Rock while being interviewed on Inside the Actor's Studio:
It's never the audience's fault. Never. Ever, ever, ever. If the movie's not good, it's my fault. TV show's not good? It's my fault. Any time I'm in front of the audience–I don't care if somebody got shot in the middle of the show–if I can't get the crowd back, it is my fault. It is my responsibility to rock the house every…single…time. No matter what."
The quote comes about 5 minutes into this clip.