Work with your child on her homework yourself. All parents need to put in some monitoring in this arena. Depending on parenting philosophy, some parents actively work with a child, some make themselves available only for quizzing and checking, and some feel that homework is to be kept between the teacher and child. If your child is doing poorly or failing, you need to take an active role. Sign your child up for a study skills course.
Some children are quite bright, but lack basic skills for organizing their work and staying on task.
Study skills courses may be offered at your child's school, through the YWCA, or through your local community college or voc-tech. Eliminate TV on school nights. Any child who is failing at school should not have access to a TV set until all homework is done and correct. Eliminate or cut back on extra-curricular activities. If sports, piano, scouts or other activities are cutting into homework time or exhausting your child, cut out those things until her grades are back up to a satisfactory level.