California Code, Education Code - EDC § 44258.1

The holder of a credential authorizing instruction in a self-contained classroom may teach in any of grades 5 to 8, inclusive, in a middle school, provided that he or she teaches two or more subjects for two or more periods per day to the same group of pupils, and, in addition, may teach any of the subjects he or she already is teaching to a separate group of pupils at the same grade level as those pupils he or she already is teaching for an additional period or periods, provided that the additional period or periods do not exceed one-half of the teacher's total assignment.