All behaviour is communication.

Hearing that phrase for the first time was a lightbulb moment for me.
No child WANTS to misbehave, of course they don't.  Why would they?
This phrase is one of the key principles of the nurture philosophy, first advanced by Marjorie Boxhall and now underpinning a national movement which you can read more about here. This statement has so much power, it changed my approach to managing behaviour permanently.
It draws me back to basic needs, what do we need for survival?
What happens when those basic needs are not met?
When a baby cries, is he misbehaving?
 As a new parent I frantically tried every option possible before finally hitting the jackpot, learning quickly that, in the case of both my boys, they were usually crying because they were hungry.  I attended to their needs and they stopped crying.  Together, we learned how to respond to one another, they eventually learned to communicate their needs effectively.
No more crying baby.
 So simple looking back, but so stressful at the time.
I got it wrong, changed a nappy or waved a rattle in front of them when they simply wanted to sleep, they showed this by crying louder, longer and harder.  I soon learned.
So, generally we have no problem in understanding that negative behaviour is communication for babies.
Where does it all go wrong?  Why do some children continue with negative behaviour?
It would be simplistic to state that all poor behaviour expressed by children of school age is because their Mum didn't change their nappy quickly enough when they were a baby, but in very simple terms, the reciprocal relationship established between child and carer is absolutely crucial to the development of the skills needed to cope with supply and demand throughout life.  Marjorie Boxhall was primarily discussing children with Attachment Disorder, stemming from a problem in the reciprocal relationship above.
All too often however, other factors interfere with a child getting what they need to feel secure. Feeling secure is crucial to development, as explained by Maslow in his Hierarchy of Need. Without security, it is difficult to form higher order skills like regulation and self-esteem.
Children with Language Disorders and delays often struggle to fit behavioural expectations in the classroom.  Perhaps they struggle for words to express their frustration because they have not developed a sufficient vocabulary.
How do you explain frustration without using the word?
An enormous number of children with whom I have had the pleasure of working are restricted in their emotional vocabulary to 'happy' and 'sad'.
Developing a stronger expressive vocabulary and ensuring children have the opportunity to use it is essential to moving them out of a behavioural rut.  Looking at pictures and discussing the feelings of people in them, giving the child scenarios and modelling or scripting their choices in order to provide an 'escape route' should they find themselves in a similar situation can help here.
All to often, the child who has repeatedly been sent in at playtime because they have hit another child, stops this behaviour once they have been taught the skills to communicate their frustration and given the opportunity to do so.  We usually learn that the 'victim' was not so innocent after all!
Communication, of course, can be non-verbal and everyone's interpretation of the world around them is different.
I referred earlier to my own education at the hands of my eldest son as I wrongly waved a rattle in front of his face only to find it made him cry even more. 'Over stimulated' cried my sister, a very experienced Super Mum, whom I called for advice every time A squeaked.
Again, most children can successfully integrate their world on a sensory level by the time they reach school, but for many, a need to calm by withdrawing from sensory input is necessary throughout primary school.  Sensory overload may lead to behavioural outbursts, repetitive behaviours such as rocking, anger or aggression.  In order to combat, we may learn behaviour to help us calm.  I bite my nails. Disgusting habit, I know.  Unfortunately, children often learn behaviours which are negative, sometimes criminal. Perhaps from role models whom are less than ideal.  Does this mean they are innately bad?
There's a whole can of worms opened right there....
The first step to successful behaviour management is to find out what the child is trying to communicate, what is the source of their frustration?  What is stopping them from functioning?  Has negative behaviour been successful for them in the past, thus becoming 'learned' so the child is now receiving mixed messages and is, as a consequence confused and simply does not understand expectations?
Poor behaviour is a cry for help, it is our duty as adults to listen.