How many school age children in ca?

There's no single, readily available number for the exact count of school-age children in California. The definition of "school-age" varies (e.g., kindergarten through 12th grade, or ages 5-17). Also, the numbers fluctuate constantly.

To find an estimate, you would need to consult data from the California Department of Education (CDE). Their website provides enrollment statistics, but you'd have to gather and potentially sum data from different grade levels to arrive at your own calculation based on your definition of "school-age."