I recently had a humorous experience with my nine year old son. 

He is a very intelligent boy who was carrying all "A's" with the exception of spelling where he was carrying an "F".  I was getting frustrated because we were studying 10 hours per week and he just couldn't get the words to stick.  So, I asked him if there was anything he really wanted that could be a prize for getting the grade up.  He thought and then replied, "Dad, I really need a cellular phone."  I have to admit to being taken back by the idea of a child using a cellular phone.  Seriously, who could be calling him? But I agreed that if he would raise his grade to a "C" I would get him a cellular phone.  He then asked, "Will it have texting?"  I said, "Sure." 

At the end of nine weeks, he had raised his grade from an "F" to a "B".  So, we went out to our local superstore and purchased a cellular phone with texting.  I spent the afternoon picking the least expensive calling plan I could find.  Then I showed him how it worked.  I showed him how the keyboard would type messages and he could send them to other people's telephones.  Shortly afterwards, I received a text on my cellular phone.  It said, "dus it werk?"  I had to conclude that it didn't work as well as I hoped.  Guess we will keep working on that spelling.

This is a great lesson though.  When the only reason someone is doing something is for a reward, once they get the reward they typically go back to doing things the way they did them before.