The view of a Rebbe:
I am a Rebbi of Grade 6 boys. From my experience, boys like and respect a Rebbi/teacher who respects them. Its a mishna – “aizehu mechubod, hamechabeid es haberiyois”.
Talmidim resent tough approach. I see myself, when getting too tough, ie shouting yelling etc, the kids hate it, and close into themselves, dislike the rebbe/teacher, and it takes time to repair the relationship.
Talk to them in a caring way, explain to them why what they did was wrong, they are good people, and the expectations are higher, the kid will not want to let you down. By building that sort of relationship with the kid, you stand far more chance.
I have the type of relationship with my talmidim, where a mere look at them as though saying why, results in them choosing the correct behaviour, because they feel they dont want to let me down/ruin their relationship with me.
All this without raising a voice or finger at them!
Two things to remember:
1)They dont mean it personally when they misbehave. This avoids the anger issue. If you do feel anger, tell the child to see after the session. By then you should have calmed down, and deal with the issue sensibly.
2) When chastisng a child, tell him/her he/she is good etc, but they made the wrong choice this time. Explain why it was wrong and what they could do differently next time. (better still, have a discussion with the said pupil, in a way that they figure it out themselves. This helps their growth)
Hatzlacha to all mechanchim out there! Its tough, but the reward is immense – lefumm tzara agra!