Badly behaved children tend to grow up into badly behaved adults!
Neither children nor animals should be shouted at or struck, or told one thing one day, and something else the next day.
The day before a parents' and teachers' evening one eleven year old said to me, "Could you tell our parents not to chop and change their minds about what we may or may not do, all the time, but to be more like you? When you say, no, I am sorry, you may not do that, we know you mean it and that someone else won't be allowed to do it tomorrow."
I thanked her for the compliment but answered that I could not tell her or anyone else's parents what they should do, but I would see if I could find a tactful way of hinting about what she had just said.
Forty years of teaching showed me very clearly, that children appreciate a few sensible rules that are kept to and that apply to everyone.
However, teaching good manners or instituting rules are two-way streets. On one occasion a pupil said to me, "You will need to shout if you want the gang to hear you" She dissolved into a fit of giggles when I replied, "Don't you think I would feel a complete idiot, shouting Be quiet? Quite apart from the fact that I was taught it is rude to shout at people."