Cal. Ed. Code § 37612
If after notice of intention has been given to establish and operate a continuous school program in a manner so as to require any pupil to enroll in a continuous school program, a petition signed by 25 percent of the registered voters of the district may be presented to the county superintendent of schools requesting that the school district not establish that program. This petition shall be presented no later than December 10th of the year in which the notice is given.
The county superintendent of schools shall examine the petition and, if he or she finds it to be sufficient and signed as required by law, order a ballot proposition, as provided by Section 37614, to be placed upon the ballot of the appropriate election as provided in Section 37613.
The governing board of the school district may request that an election be called and conducted irrespective of whether or not a petition is presented.
Ca. Educ. Code § 37612