24 Pa. Stat. § 13-1301
Every child, being a resident of any school district, between the ages of six (6) and twenty-one (21) years, may attend the public schools in his district, subject to the provisions of this act. Notwithstanding any other provision of law to the contrary, a child who attains the age of twenty-one (21) years during the school term and who has not graduated from high school may continue to attend the public schools in his district free of charge until the end of the school term. The board of school directors of any school district may admit to the schools of the district, with or without the payment of tuition, any non-resident child temporarily residing in the district, and may require the attendance of such non-resident child in the same manner and on the same conditions as it requires the attendance of a resident child.
24 P.S. § 13-1301