Cause and effect, that's what kids need to understand!  Now I know that they understand what happens if they upset YOU, but because you are the GREAT PROTECTOR, children don't always realize that there are consequences at school, too.  To me, this is the true curriculum.  We are teaching your child that in the real world, there are consequences for what we do.  Some of you are already thinking that I am talking about punishment, but I haven't forgotten rewards.  When your child does something kind and good, s/he is met with big smiles and twinkley eyes and possibly even a hug.  Praise counts as a consequence, as well.  Here's the tricky part:  There is more than one child in the room and all of them want attention.  Teach your child to value that smile or that twinkle in the teacher's eye just as much as the hugs and cash that YOU can provide for them.  Hugs are not always appropriate in the hustle and bustle of the classroom setting, but I guarantee you that we give your 
child all the hugs we can spare, when the time is right.

Intangible Positive Consequences:

A Smile
A Wink
The OK Signal
A Nod
A Pat on the Back or Shoulder
Verbal Praise in a Gentle Tone of Voice
The Teacher Saying Thank You

Negative Consequences that come before Discipline:

Your Name, With Emphasis on the Last Syllable (GooBER!!)
A Furrowed Brow With Direct Eye Contact
Pursed Lips
The Look of Death and Destruction Followed by the Saying of Your Name in a Deep Tone of Voice

I think you get the picture.  
I suggest you practice the above with your child.  
It is important that he or she know when to laugh and when not to...

Thanks