In a recent workshop, a teacher commented, "My students who are high ability just take learning for granted. Because of this, they seem lazy and unwilling to work."
I taught the student described in this statement. He had always been the smartest student in the room, and his parents continually praised his ability. However, over time, he felt like he was so smart, he didn't need to try anymore. He assumed his ability would carry him through my class.
A recent study clarifies this situation. The researchers found that if students are praised only for their ability, over time, their effort and achievement goes down. But if you praise a student for effort, for working hard and being persistent, over time they increase their effort, and their achievement increases. You can mix the two, but don't forget effort. Over time, it does make a difference with your students.