A bad grade once in a great while is no big deal. Even the reason for it is not so important if it only happens very occasionally. This applies to things like a single day's homework, a specific test, or individual assignments. It does not apply to grade cards or to whole subjects. They represent many grades over time. If your child gets a D or F on his grade card or frequently gets bad grades in a specific subject, he has a problem.
What is a bad grade? It is not unusual to hear someone say, "He could get A's if he wanted to," although children who can get A's by making a reasonable effort get A's. If he does not get A's, either he really cannot or it would take a super- human effort. Some extra effort is good. If it goes too far, the good grade comes at the expense of other activities and at a very high cost in stress and pressure. The A is not worth it. Perfection can be given far too much importance.
Keep this in mind. C's are average in most schools. Average children get mostly C's. If he is getting mostly C's or a C among the B's, let him know you think he is doing fine. A little pep- talk to get him to hang in there and give it his best is okay. Any more pressure than this is a bad idea. It can actually make things worse.
If you expect higher than average grades for your child and they are not forthcoming, be very sure you have clear evidence he (or she) really can do better without unreasonable effort. Beyond assuring your child spends an appropriate amount of time doing school work, be prepared to provide qualified tutoring and other assistance that may be needed. Just pressuring your child to study more and work harder typically does not help and often makes things worse.
Bad grades are D's and F's. If your child is getting bad grades in one or two subjects or in most subjects, there is a serious problem.
First, suspect a reading problem. There usually is one. Next, consider the full range of possible learning problems. Keep looking until an answer is found. When you see this sign, it is unlikely it is your youngster's fault or he can do anything about it by himself. If someone tells you he just needs to try harder, find someone else who really can help you and your child figure out what's wrong.