California Code, Education Code - EDC § 37223

(a) The governing board of any elementary, high school, or unified school district or any county superintendent of schools may maintain classes on Saturday or Sunday, or both.  The classes maintained pursuant to this section may include, but are not necessarily limited to, all of the following:

(b) Except as otherwise provided in this code, the attendance of any pupil in a class or program held on a Saturday or Sunday shall not result in the crediting of more than five days of attendance for the pupil per week.

(c) Attendance at classes conducted on Saturday or Sunday, or both, shall be at the election of the pupil or, in the case of a minor pupil, the parent or guardian of the pupil.  However, the governing board may require truants, as defined by Section 48260, to attend makeup classes conducted on one day of a weekend.

(d) Except as otherwise provided in this code, any class that is offered on a Saturday or Sunday shall be one offered during the regular Monday through Friday school week.

(e) The voluntary attendance of pupils enrolled in programs for gifted and talented pupils in special educational activities conducted on Saturday or Sunday shall not be included in the computation of the average daily attendance of the school district.

(f) Subdivisions (b) and (d) shall not apply to regional occupational centers or programs.