The grants come with strings. Recipients will have to teach a subject in high demand, such as math, science, special education or a foreign language. They must commit to teach at least four years in an area where there is a shortage of educators.
Recipients get eight years after graduation to fulfill their obligation. If they don't, the grants convert to unsubsidized student loans, and they will owe not only the principal but accrued interest.
It is being used as incentive to make sure people keep their end of the bargain.