According to The Cute Kid, parents tend to overreact to disappointments such as bad grades on their child's report card. It's important to give yourself some time and space to deal with your own disappointment and emotional attachment to your child's performance. You may also choose to talk about a unified front with your spouse regarding how you want to respond to her grades. Dealing with your emotions first will help to find a logical solution to the grades and inspire trust and confidence in her relationship with you.
Ask your child about what led him toward getting the bad grade, whether it was one or two bad tests or if it's a specific subject area in which he is struggling. Rather than accusing him of having poor character traits, such as laziness or apathy, give your child a chance to explain his perspective and brainstorm on possible solutions for success on the next report card. Although you may choose to offer some suggestions, make a plan with your child instead of planning for your child.
Search for the root cause of the grades rather than assuming that she isn't studying enough or is hanging out too much with her friends. If she is struggling in a certain subject, she may need a tutor or extra time spent with her teacher after school. Contacting the teacher can also lead to some insight on what your child needs to succeed in class. Establishing a better relationship with her teacher can help with monitoring and tracking your child's progress throughout the next grading period by knowing the teacher's schedule for upcoming tests and major assignments. If your child simply needs to dedicate more time to schoolwork, remove another time drain such as Internet access or television. Alternatively, you may choose to find out how your child's friends are doing in their classes and see if habits influenced by your child's immediate peer group may be part of the problem.
Although it may be difficult not to worry about your child's grades, give him the benefit of the doubt if this is his first time bringing home a bad report card. Work with him and allow him to learn from his own mistakes instead of treating him poorly throughout the next grading period. Remember that you are responding to his behavior and not to him as a person. Encourage and inspire confidence in your child while holding him accountable for his studies. Celebrate his successes rather than reminding him of the need to improve.