Never point out other peoples wrong behaviour in public.

Todays lecture at the catholic mass: (Matthew 18:15) “If your brother or sister sins, go and point out their fault, just between the two of you. If they listen to you, you have won them over.”
Source (English version at 18:15 http://www.biblestudytools.com/matthew/18.html)

The Swedish version does not talk about sin but about something bad. (“Om din broder har gjort dig någon orätt…“) That change makes the quote more useful, e.g. in the classroom.

A similar rule  is found in the Quran.

I stopped pointing out a students fault in public in the classroom many years ago.  
Not because  Jesus said that ( I did not know about this verse) but because I have learned that by experience.  by poinint out fqult in public I did not get the  results i wanted. It happened even that I lost a good contact with that pupil. And I also  interrupted my lesson and got my pupils to  talk and think  about other issues instead.

By waiting to after the lesson you can have a good dialog and let the alumni come to a good conclusion and maybe ask for pardon.

And you can help the pupil find strategies how to avoid to “sin” again.

I have learned that one should only give positive feedbacks and avoid negative ones.

Eg, never say “Your answer is wrong“.  beacause this gives you a silent class.
It is better to say “Very intresting, can you tell us how you came to this conclusion?” or maybe
“Very intresting answer. What do you comrades think about ____’s answer? Do you agree about that answer?” By doing this you get a dialog in the classroom.