Section 41A. The school superintendent may grant a leave of absence for study or research to any teacher, registered nurse, principal, supervisor, director, school librarian, school business administrator, or assistant superintendent, serving at discretion which would increase his professional ability, such leave to be for a period not exceeding one year at full or partial pay; provided, however, that prior to the granting of such leave he shall enter into a written agreement with the superintendent that upon termination of such leave he will return to service in the public schools of such city or town for a period equal to twice the length of such leave and that, in default of completing such service, he will refund to the city or town an amount equal to such proportion of salary received by him while on leave as the amount of service not actually rendered as agreed bears to the whole amount of service agreed to be rendered. A school superintendent may also grant a leave of absence to any teacher, registered nurse, principal, supervisor, or school business administrator, serving at discretion for service to a statewide professional education organization of which such teacher, registered nurse, principal, supervisor, or school business administrator is a member and has been elected to hold the office of president therein, such leave to be for a period not exceeding four full years at full or partial pay; provided, however, that such professional education organization shall reimburse the school committee for any salary paid to said teacher, registered nurse, principal, supervisor, or school business administrator during such period. Any employee granted a leave of absence under this section may receive compensation from any grants or gifts received for the purpose of this section pursuant to section thirty-seven A, as well as from funds appropriated therefore.

Any teacher, registered nurse, principal, supervisor, director, school librarian, school business administrator or assistant principal who is elected or appointed to a state office, or elected by the people to the office of mayor, shall upon his written request made to the school superintendent, be granted a leave of absence without pay for such position for all or such portion of the term for which he was elected or appointed as he may from time to time designate, and shall not as a result of such election or appointment, be suspended or discharged or suffer any loss of rights. Any person granted a leave of absence under the provisions of this paragraph shall not be subject to the provisions of section thirty-eight G during the period of such leave.

A school committee may grant a leave of absence for study or research, or for service to a statewide professional education organization, and shall grant a leave of absence for service as an elected state official or elected mayor, to a school superintendent under the same terms and conditions as are described above for leaves granted to other professional staff.