Would it be possible for police academies to offer a subset of police officer training that omitted the parts that would not be needed (eg traffic enforcement, police driving, forensic techniques, investigation, etc) for a teacher who wanted to take on the responsibility of keeping their students safe, which could be done during summer vacation (when teachers are off work anyway)?
The teachers would of course be subject to the same background check requirements as police officers and would be granted a very limited law enforcement power on school grounds (basically dealing with shooters and violent situations), having received the full police firearm training.