Cal. Ed. Code § 38110
The county board of education shall on or before the first day of February of each year establish rules and regulations under which any school district in the county shall, except as provided in Section 40002, purchase standard school supplies and equipment through the county superintendent of schools, or when so directed by him or her, through a county purchasing agent.
When the county superintendent of schools purchases standard school supplies without directing their purchase through the county purchasing agent or other county, city, or school district agent or agency, he or she shall make such purchase from the lowest responsible bidder who shall give such security as the county superintendent of schools requires, or else reject all bids. For the purpose of securing bids, the county superintendent of schools shall publish at least once a week for two weeks in a newspaper of general circulation published in the county, a notice calling for bids stating where the list and specifications of standard school supplies and equipment to be furnished may be obtained and the time when, and the place where bids will be opened.
The county board of education shall list as standard school supplies and equipment such supplies and equipment as can be advantageously purchased in quantity. The list of standard school supplies shall be accompanied by a table of specifications giving the minimum grade, quality, substance, or other standard required for the purchase of each item listed.
The cost of advertising for bids and the cost of preparation of a table of specifications shall be paid from the county general fund.
The provisions of this section shall not apply to counties of the first or second class containing no more than three districts with an average daily attendance of less than 2,500.
Ca. Educ. Code § 38110