Cal. Ed. Code § 1270
The county superintendent of schools of any county may use schoolbuses to transport pupils attending schools or classes operated by the county superintendent pursuant to Article 15 (commencing with Section 1920) of Chapter 6 of this part, including adults attending special classes for adults designed to serve the educational needs of handicapped adults operated pursuant to Section 52570, and teachers or other employees employed by the county superintendent of schools, to and from school athletic contests or other school activities, or to and from fairs or expositions held in the state or in any adjoining state and in which the pupils participate actively or as spectators. The transportation may be provided on any day or days throughout the school year.
Ca. Educ. Code § 1270