Most seventh-graders don't care about grades. There are other markers to look for, such as how a child tests, and how happy she is.
My 12-year-old daughter tests well, but she won't do homework, so her grades are not great. She is happy and has lots of friends and activities. She wins essay contests and shows genius in many areas, but not school. How do I get her to care about her grades? The teachers tell me she takes the tests, but she does very little homework. I honestly think she doesn't care about grades.
Most seventh-graders don't care about grades. Keep in mind that she is smart, tests well, and is happy. That said, she does have to do the homework or she will not test well, will not be smart, and eventually will not be happy. To get homework turned in, there has to be a system of consequences and rewards until it becomes a habit. Make sure she has a predetermined time and place for study (without TV or computer; quiet music is okay); assistance from you or your husband whenever necessary; an assignment notebook that you check every day; consequences, like going back to school to get her forgotten homework; a single binder with dividers and pocket notebooks that she takes to every single class; assignments put in appropriate section of binder; binder put in backpack; backpack put by door.
Check every day for a couple of weeks. Then, extend the time between checking. Offer rewards for handing in all assignments, no matter what grade she receives. Check with teachers and the school counselor for other ideas. At this point in a teen's life, parents have to be parents and set the boundaries for the child. It's a lot of work, even though the final responsibility is hers.