24 Pa. Stat. § 5-517
The board of school directors of each district may authorize the attendance of the superintendent and such other members of the teaching and supervisory staff of such districts as they may specify, at any educational conference or conferences, when in the opinion of the board, such attendance will be conducive to the best interests of the district. Each person so authorized to attend and attending shall be reimbursed for all necessary traveling and hotel expenses actually incurred. The board of school directors may also authorize the transportation of pupils to the State Farm Show and to other exhibitions and places of interest, when their attendance at the same is deemed of educational value to such pupils, and may pay the expenses of such pupils, in whole or in part, from the funds of the district. Such expenses shall be paid by the treasurer of the school district, in the usual manner, out of the school funds of the district, upon the presentation of an itemized, verified statement of such expenses.
The board of school directors of each district may reimburse any principal, supervising principal, school nurse, teacher or other employe for necessary traveling expenses incurred in the furthering of the educational program of the school district: Provided, That prior authorization to incur said expenses shall have been previously given by the board of school directors: Provided further, That advanced payments may be made by the proper officers of the district upon presentation of estimated expenses to be incurred, to be followed by a final itemized, verified statement of such expenses actually incurred upon return from such conventions, and a refund be made to the district of such funds remaining or an additional payment be made to meet the verified expenses actually incurred.
24 P.S. § 5-517