“Over 30 years ago, Carol Dweck and her colleagues became interested in students' attitudes about failure. They noticed that some students rebounded while other students seemed devastated by even the smallest setbacks. After studying the behavior of thousands of children, Dr. Dweck coined the terms fixed mindset and growth mindset to describe the underlying beliefs people have about learning and intelligence. When students believe they can get smarter, they understand that effort makes them stronger. Therefore, they put in extra time and effort, and that leads to higher achievement.

What is the topic sentence in this paragraph above?

The topic sentence in this paragraph is: "Over 30 years ago, Carol Dweck and her colleagues became interested in students' attitudes about failure."