Which type of ordnance must not be used for classroom training?

Live ordnance must not be used for classroom training due to the inherent risks and dangers associated with handling explosive materials. Live ordnance contains explosives that can detonate, causing potential harm to students and instructors. Safety is a paramount concern in training environments, where the focus should be on learning and skill development without the risks posed by functioning munitions.

In contrast, certified inert ordnance is designed specifically for training and education; it simulates the appearance and functions of live munitions without the risks of explosion or detonation. Expended ordnance refers to items that have already been used and are no longer capable of detonation, making them safe for educational purposes as well. Thus, while inert and expended ordnance can be utilized effectively for training, live ordnance poses unacceptable safety hazards in such settings.