Offering cash payments or gift certificates for good grades actually decreases learning outcomes in the long run, and often encourages cheating. This is especially true for courses in technical subjects or mathematics.
A few research studies have shown that cash payments produce a limited improvement in behaviors that are easy for the student - like wearing a uniform or going to the library. However, when the task takes diligent work, like learning math concepts, the payments are actually detrimental in the long run.
The best way to get a student to do something that requires diligent work is to increase their intrinsic motivation to learn. Some have argued that if a student has very low intrinsic motivation to learn, cash payments or other significant extrinsic forms of motivation might jump start the learning process and give students a positive experience that eventually leads to an increased intrinsic motivation to learn.
Two of the most respected researchers in this field are Richard Ryan PhD and Edward Deci PhD who both work at the University of Rochester. Their research shows that cash payments and other significant extrinsic forms of motivation actually decrease a student's natural internal motivation. They also have developed and tested an effective system for building internal motivation to learn.
The Smashing Silos Research Staff