Cal. Education Code § 44929.25

When a teacher of classes for adults serves sufficient probationary time as provided in Sections 44929.20 to 44929.23, inclusive, and Section 44908 to be eligible for election to permanent classification in that district, his or her tenure shall be for the service equivalent to the average number of hours per week that he or she has served during his or her probationary years. In no case shall the employee be classified as permanent for more than one full-time assignment. The service for which the person has acquired tenure may be reduced in conformity with Sections 44955 and 44956. Notwithstanding any other provision to the contrary, in a district that has, or in a district that is one of two or more districts governed by governing boards of identical personnel that have a combined average daily attendance of 400,000 or more, as shown by the annual report of the county superintendent of schools for the preceding fiscal year, no person who is assigned 10 hours or less a week in adult classes in the district shall be eligible for election to permanent classification in the district on account of the assignment in adult classes. Notwithstanding any other provision to the contrary, any person who is employed to teach adults for not more than 60 percent of the hours per week considered a full-time assignment for permanent employees having comparable duties shall be classified as a temporary employee, and shall not become a probationary employee under the provisions of Section 44954.