Many perspective airplane pilots feel that flight training is simply too time consuming and too expensive. Sport pilot solves this time/money issue by creating a basic, entry level pilot certificate that is paired down to train people for only the things they use as a airplane pilot without jeopardizing safety. The result is a pilot certificate that is half the time commitment and half the cost of a private pilot certificate.
If you are a current airplane certified flight instructor (CFI), you now have the opportunity to expand your operations by instructing sport pilot candidates in any aircraft you are currently rated. For example, if you are a CFI with a SEL rating can instruct a student in an SEL airplane for a sport pilot certificate with no additional requirements.
For more information on existing (Subpart H) CFIs instructing sport pilots, CFI Operating as a Sport Pilot Instructor.