38 C.F.R. § 21.5870
(a) Credit hour measurement: undergraduate, standard term. An individual who enrolls in a standard quarter or semester for 12 undergraduate credit hours is a full-time student. An individual who enrolls in a standard quarter or semester for less than 12 undergraduate credit hours is a part-time student.
(Authority: 10 U.S.C. 2144(c))
(b) Credit hour measurement: Undergraduate, nonstandard term.
(1) If an individual enrolls in a nonstandard term, quarter or semester, and the school measures the course on a credit-hour basis, VA will determine whether that individual is a full-time student by—
(2) In determining whole weeks VA will—
(c) Credit hour measurement: graduate.
(d) Clock hour measurement.
(2) If an individual enrolls in a course measured in clock hours and theory and class instruction predominate in the course, he or she is a full-time student enrolled in 18 clock hours or more per week. He or she is a part-time student when enrolled in less than 18 clock hours per week. Customary intervals not to exceed 10 minutes between classes will be included in measuring net instruction. Shop practice, rest periods, and supervised study are excluded. Supervised instruction periods in schools' shops and the time involved in field trips and individual and group instruction may be included in computing the clock hour requirements.
(Authority: 10 U.S.C. 2144(c))