Ex-police and worked in schools. I dont believe your son for a second.

I'm also suspicious about why you keep calling it "an item". What was it?

Legally, teachers are allowed to use reasonable force against pupils in order to impose control or to prevent damage/injury to that pupil, any other pupil, school property or staff. They also have the same common law rights to use force as any other member of public. There's no requirement in law to issue a verbal command. As you're being so deliberately vague with the circumstances I also suspect that perhaps there wasnt time or opportunity to say anything any way.

The police will (should) only get involved if the matter has already been investigated by the school and education department and police involvement is believed to be warranted, or the offence is so serious and clearly a breach in law.