My brother was like this at school, A+ in area of interest, barely passing the rest. Interestingly it took him about 5 years after school to discover that he needed to work in all areas to get what he wanted. He now is a teacher (in the top 1% when studying), loves his kids and work, is the GT co-ordinator and working on ways to engage kids like he was. Lets hope it doesn't take your DD quite that long!