In a charter school, for the purposes of Education Code section 51745.6, the ratio of average daily attendance for independent study pupils to full-time equivalent (FTE) certificated employees responsible for independent study shall not exceed a pupil-teacher ratio of 25:1 or the ratio of pupils to full-time equivalent certificated employees for all other educational programs operated by the largest unified school district, as measured by average daily attendance, as reported at the second principal apportionment in the prior year, in the county or counties in which the charter school operates. Units of average daily attendance for independent study that are ineligible for apportionment as provided in subdivision (b) of Education Code section 51745.6 shall also be ineligible for funding pursuant to Chapter 6 (commencing with section 47630) of Part 26.8 of the Education Code. For purposes of this section, a “full-time certificated employee” means an employee who is required to work a minimum six-hour day and 175 days per fiscal year. Part-time positions shall generate a partial FTE on a proportional basis.