A famous study was done in a school by a professor   from a university. At the start of the school year, the teachers were given the names of five children. They were told that these five were the most excellent students in the class. But the fact was that these students were only average ,and they were not the best students at all. Well, guess what? At the end of the year, all the five average students scored among the highest in the class. What made these average students change so much to become top students?The only difference was the change in their teachers' attitude . Because the teachers believed that these five kids were the top students,they expected  more from them. And so these five average students began to believe and expect more from themselves. So they worked harder to do as well as they could. Do you know why? If you expect the best from people, they'll usually want to give you their best. A great leader said, "Treat  a person just how he appears to be on the outside, and you'll make him even worse. But treat a person like he's already a success,and you'll help make him the best he can be." Like the true story of 7-year-old Johnny, his teacher got so angry with him that one day she said,"Johnny,you're the naughtiest  boy in this class. I'm sure you'll never change." The next year Johnny had a new teacher. And on the first day of class,she met with Johnny after school and said,"Johnny, I've heard a lot about you! But do you know that I don't believe a word of it." And every day after that, this new teacher treated Johnny as if he was one of the smartest students even when Johnny did naughty things. Later on, Johnny became a school leader. Because that's the power of our belief  and attitude  toward children. The five average students became top students mainly because of   _  .
the professor's study the teachers' hard work the change in the teachers' attitude the change in the professor's attitude