Mass. Gen. Laws ch. 71 § 13
In every public school having not less than one hundred and fifty pupils, any course not included in the regular curriculum shall be taught if the parents or guardians of not less than thirty pupils or of a number of pupils equivalent to five per cent of the pupil enrollment in the high school, whichever is less, request in writing the teaching thereof; provided that said request is made and said enrollment is completed before the preceding August first; provided, further, a qualified teacher is available to teach the course; and provided, further, that the approval and implementation of said course is voted by two-thirds or more of the full membership of the school committee. The teaching of any course as provided by this section may be discontinued if the enrollment of pupils falls below fifteen. Such courses as may be taught under this section shall be given the same academic credit necessary for a high school diploma as is given to similar courses taught in said public high school, provided that the school committee shall make a determination as to the credit equivalency of such course prior to its being offered.
Mass. Gen. Laws ch. 71, § 13