There are a variety of ways to calculate per-pupil spending. Each has advantages and disadvantages, depending on the intended use of the data. For example, one measure might be useful for comparisons between states, while another measure might be more useful in state budget discussions.
The links below provide historical data for the current expense of education, which is calculated at a school district level, and a comparison of the different methods.
Current Expense of Education
Calculation of current expense (cost) of education per average daily attendance (ADA) pursuant to Education Code Section 41372.
Comparison of Per-pupil Spending Calculations
Comparison of different methods for calculating per-pupil spending.