Types of Petitions: Exceed the IAP Credit Limit
All MIT undergraduates are subject to a 12-unit credit limit during Independent Activities Period (IAP). Note that the CAP very rarely allows any exceptions to the IAP Credit Limit. An exception might be granted for a student expecting to complete a degree with an IAP overload.
The Independent Activities Period aims to provide "a welcome break from the academic routine of the fall and spring semesters. It offers opportunities for creativity and flexibility in teaching and learning. Students are encouraged to set their own educational agendas, pursue independent projects, meet with faculty, or pursue many other options not possible during the semester." (Quoted from IAP website.) The 12-unit limit was imposed precisely to prevent students from committing to so much "academic routine" that creativity and flexibility get squeezed out.