This credential authorizes the holder to teach the specific subject(s) named on the credential in departmentalized classes, such as those in most middle schools and high schools, in grades preschool, K–12, or in classes organized primarily for adults. California has a two-level teaching credential. To obtain a Preliminary Credential which is valid only for 5 years, the following requirements must be met: Obtain a baccalaureate degree. Satisfy the basic skills requirement. Satisfy the subject-matter competence requirement.