I had one of those, "I know", children.

They are being "wise in their own eyes" and it's pride and can be a bad habit. I talked to her about the verse quite often and I also said, "no, you don't know, it's not true that you know so you need to stop saying that", or something along those lines.
Excuses are an ugly habit, for adults as well. I think it's a big one to stifle now while they are young. I know adults who have an excuse for everything, very annoying. (okay okay I have an excuse every once in awhile, but it's not my fault because....)

Do not allow any excuses, she is probably doing it in other areas as well, besides school. If you start paying attention you'll probably see that. I would come up with some way to show her nicely for awhile when she is making an excuse (some little sign or something) so she can start recognizing it and give her something else to say instead. Several years ago my sister and I decided to pay attention to ourselves and notice any time we started making an excuse about something, even if we had a legitimate one, and stop ourselves from giving it. If we were late somewhere, it's easy to blame it on the traffic, others in the family, slept late, whatever, true or not, but just not say anything or say, "I'm sorry I'm late" and leave off the excuse! It was an eye-opener. Maybe you can all work on it as a family or something like that.
About the schoolwork though, I would definitely cut her off and let her know what an acceptable reply would be. Have her practice.
Oh, I forgot to mention. The daughter who did that, does not anymore! It really worked, I was consistent in not letting her do it and I think her spirit really responded to the Scripture and why it's wrong.
Nancy
(I think I'll start listening to myself again and see how I'm doing! )
