The thing is @HaudYerWheeshtYaWeeBellend that a lot of teachers are currently having to put up with violence and threats, with no police involvement, just constant suggestions from management about what they should be doing differently. It is a massive issue, not in all schools but in far too many.
I agree, one of our senior schools teachers were assaulted by a pupil in front of the head, teacher called the police, (they broke a rib) head didn’t want police intervention 
Another primary school teacher was assaulted, head called the police, parents kicked off, teacher was knocked out cold.
(Both of these were a few years apart, there needs to be a clear no violence policy, however I don’t blame the teachers trying their best, I blame the government, you can’t do X,Y and Z with children, you must try X,Y and Z with children, you can’t do that as you may hurt their feels or emotionally distress the child, all the while the teacher/social worker has been knocked out unconscious and the parents laughing
(^^that was recently)
There needs to be a clear, simple, consistent message that all types of abuse will not be tolerated and that appropriate punishment will be enforceable no matter the circumstances.