I don't think its always right to teach what is right and what is wrong, our children understand right from wrong at an early age, because we have to teach it to keep them safe. So I would on there level explain as simply as possible why its wrong, and what "we" will do different. Such as ..."It's not nice and we do what is nice always"...that way the kids make the connection "its not nice" that most children understand early and can comprehend and repeat it correctly when necessary. As they grow older, you can increase the level of words as their comprehension of language increases.
