Any district not maintaining a high school or school of corresponding grade shall pay for the tuition of any pupil who with parents or guardian resides in said district or who, as a resident of said district, is determined to be entitled to have his or her tuition paid by the district where the pupil resides, and who attends an approved public high school or public school of corresponding grade in another district, an approved public academy, or a private school approved as a school tuition program by the school board pursuant to N.H. Rev. Stat. § 193:3, VII. Except under contract as provided in N.H. Rev. Stat. § 194:22, the liability of any school district hereunder for the tuition of any pupil shall be the current expenses of operation of the receiving district for its high school, as estimated by the state board of education for the preceding school year. This current expense of operation shall include all costs except costs of transportation of pupils.