Grand Traverse Academy 2018-19 Secondary Course Catalog 28 10, 11 or 12 are enrolled in at least one high school course, are considered full-time (through a combination of GTA and college classes), are on track to graduate with their class, and have successfully completed all GTA required courses for their class level to date, are eligible to enroll and take college or university courses through Northwestern Michigan College. Our complete dual enrollment policy is available in the Secondary office or through the guidance counselor.