This seems to vary by state. For example, a quick google search revealed the following regulation for Texas:
Every room or space greater than 250 ft2 (23.2 m2) and used for classroom or other educational purposes or normally subject to student occupancy shall have not less than one outside window for emergency rescue that complies with all of the following, unless otherwise permitted by 14.2.11.1.2 [Which would not apply in this case]