you have already received an excellent response. I am not a child specialists but there is a forum on med help for children's behavior and you might ask your question there.
Hello. This could indicate different conditions. You can have her evaluated by a professional who may reccomend medication or other therapy. Also, she might just need assistance with her schoolwork such as using a tutor or even a private educational program such as Sylvan learning center in addition to a standard education. Hope this helps, GM
even my daughter do this sometimes,it seems she cannot do math but sometimes she is doing so easily that make me feel that may be when she has interest she does when she donn`t have she doesn`t.