There is already a state mandate similar to this in Minnesota:
http://www.homeedmag.com/lawregs/minnesota.html
Subd. 10. Requirements for instructors. A person who is providing instruction to a child must meet at least The following requirements:
(1) hold a valid Minnesota teaching license in the field and for the grade level taught;
(2) be directly supervised by a person holding a valid Minnesota teaching license;
(3) successfully complete a teacher competency examination;
(4) provide instruction in a school that is accredited by an accrediting agency, recognized according to section 123B.445, or recognized by the commissioner;
(5) hold a baccalaureate degree; or
(6) be the parent of a child who is assessed according to the procedures in subdivision 11.
Subd. 11. Assessment of performance. (a) Each year the performance of every child who is not enrolled in a public school must be assessed using a nationally norm-referenced standardized achievement examination. The superintendent of the district in which the child receives instruction and the person in charge of the child's instruction must agree about the specific examination to be used and the administration and location of the examination.
(b) To the extent the examination in paragraph (a) does not provide assessment in all of the subject areas in subdivision 9, the parent must assess the child's performance in the applicable subject area. This requirement applies only to a parent who provides instruction and does not meet the requirements of subdivision 10, clause (1), (2), or (3).
(c) If the results of the assessments in paragraphs (a) and (b) indicate that the child's performance on the total battery score is at or below the 30th percentile or one grade level below the performance level for children of the same age, the parent must obtain additional evaluation of the child's abilities and performance for the purpose of determining whether the child has learning problems.