(1)    Except as provided in s. 120.12 (25):

      (a)    No child may be admitted to a 4-year-old kindergarten unless he or she is 4 years old on or before September 1 in the year that he or she proposes to enter school.

      (b)    No child may be admitted to a 5-year-old kindergarten unless he or she is 5 years old on or before September 1 in the year he or she proposes to enter school.

      (c)    No child may be admitted to the 1st grade unless he or she is 6 years old, on or before September 1 in the year he or she proposes to enter school.

   (2)   A resident over 20 years of age may be admitted to school when in the judgment of the school board the resident will not interfere with the pupils of school age.

   (3)   

      (a)    Except as provided in par. (b), if a school board establishes a 4-year-old kindergarten program, the program shall be available to all pupils eligible for the program under sub. (1) (a) or s. 120.12 (25).

      (b)    A school board that was operating a 4-year-old kindergarten program in the 2007-08 school year that did not comply with par. (a) shall make a 4-year-old kindergarten program available to all pupils eligible for the program under sub. (1) (a) or s. 120.12 (25) by the beginning of the 2013-14 school year.