Appeal to their sense of greed. Cold hard cash can be a good motivator for your child. Set a price on grades and reward your child with a dollar for every B and five dollars for every A. Rewarding with prizes can also be a good way to get more studying out of your child.
Celebrate success. If you don't want to put a price tag on grades, try using celebrations such as a nice dinner or a special ice cream treat for hard work and improvement. Kids will benefit from a reward for good grades in school, but they may need to be motivated by simply improving their grades first.
Use awards and certificates to help kids get into gear with their school work. Seeing an award with their name on it for moving up to a B from a C average is certain to help them strive to do even better.
Be spontaneous. Another way to reward good grades in school is to give them a surprise after an accomplishment. Watch your child for self motivation and hard work and give them an unexpected bonus for motivating themselves. This way your child won't come to put a price tag on motivation, but will see that learning can be its own reward.