(1) The board of directors of a school district has the authority but is not required to permit students enrolled in a private or parochial school to attend the schools of the district on a part-time basis; however, in determining the constitutionality of a particular shared-time program, each case must be determined by its own facts. See, Perry v. School Dist. No. 81 , 54 Wn. (2d) 886, 344 P. (2d) 1036 (1959). (2) The district may not claim or use such attendance in computing its average daily attendance pursuant to chapter 28.41 RCW, unless such student attends for a school day as defined by RCW 28.01.010.