N.Y. Comp. Codes R. & Regs. tit. 15, § 46.3 – Use.

(a) Such signs shall be displayed and such flashing red signal lamps shall be used only when the vehicle is engaged exclusively in the transportation of pupils, teachers and other persons acting in a supervisory capacity to and from school or school activities. When the vehicle is not so engaged, such signs must be covered or removed. Such signs and lamps shall not be displayed or used when the vehicle is engaged in charter operations not related to school or school activities.
(b) For the purpose of this section, the term school activities shall be defined as “any program for the benefit of pupils, sponsored and supervised by school officials,” and shall include, but shall not be limited to, such activities as the following, when so supervised and sponsored:
1. (1) extracurricular activities such as athletics, dramatics, and musicals;
2. (2) field trips directly connected with subjects included in the school curriculum; and
3. (3) school dances and other similar activities.