I've started my two little ones on the chart system where good behaviour is rewarded with a smiley. I read that this way, certain modification of behaviour is possible. I tried and the results so far has been pretty positive. Why I did it? It was spurred by my desire to push my daugther who is sitting for the primary school leaving exams in Oct. And the prelims results that she recently received did not quite as much assure me of her doing well for the actual exams.
So, one day as I mulled over how to motivate her, I read about the behaviour modification through the rewards system. I set the rules, of course and she agreed - she has to : it is like a contract - and to ensure better chances of success, she should be empowered some say in the contract. ;)