Like lucounu said, I would recommend not emphasizing the grades. Instead I would stress the importance of developing the habit of carefully checking one's work. I was frustrated with DD8 missing easy questions in school this year because she would completely skip over them. She's learning it's worth the effort to review something before turning it in since otherwise the consequence is getting additional work at home. One of her classmates gets grounded for every question missed so I haven't gotten any grief about being unfair.
