Three guys in uniform are teaching nine kids to rightfully walk with spear holding.
Drie mannen in uniform leren negen kinderen recht te lopen met speer.
Three men are training their children.
Drie mannen trainen hun kinderen.
There is no reason to assume the men are training their own children, the kids parents could be elsewhere.
Er is geen reden om aan te nemen dat de mannen hun eigen kinderen trainen, de kinderen kunnen ergens anders zijn.