I don't know that it helps anything for the school to know the circumstances, but you are better able to assess that for you than I. In my case, I deal with grades and behaviors very specifically, (regardless of what is happening at home) there are expectations.
I get the F's and alot more (I have a D that see's a C once a week and will for quite awhile b/c of serious self-destructive behaviors), IMO if you deal with that instead of projecting what might have caused it and/or feeling guilty it works and then you don't have a cast of folks with alot of personal info.
Make sure the kids know you're always available to take about anything with them esp anything that's important to them. They have their friends too (not always a good thing) and if you think it's necessary take them to see a C.
