In this task, you're given an article and an answer. Your task is to generate the fill-in-the-blank question for this answer based on the given article. The blanks are always at the end of the question, and can be filled with more than one word or phrase.

Article: When I was in elementary school, my teachers would always complain about my behavior in class. There was no doubt that I had a great deal of energy, and therefore I was always talking with my classmates and not paying attention to the lessons, which my teacher _ to see. If you don't believe me, the comments on my report cards every year can tell the story. In my third year in elementary school, my teacher wrote, " Neil should tend to have a more serious attitude towards his schoolwork." And in my fifth year in elementary school, my teacher wrote, " Neil is not a bit strict with his work, his compositions as well as his notebook and so on. He has to be encouraged and urged by his parents or teachers." After only a few months, my sixth-grade teacher wrote, " Less social involvement and more academic diligence is in order." Later that same school year, my sixth-grade teacher noticed that all my book reports were about the universe. Knowing that I had a lot of extra energy, she recommended that I should take advanced after-school classes about the universe at the Hayden Planetarium. From then on, my love of the universe became stronger and stronger. Instead of killing my time in class, I focused my extra energy on the subject that would be bound to become my career. Between the ages of eleven and seventeen, I took about eight courses on the universe. For each one, I received an attractive certificate of completion, signed by both the teacher and the head of the Hayden Planetarium. We still offer these classes today. And we still give out certificates of completion, which are signed by the teacher and, of course, the head --- me. I am the head of the Hayden Planetarium. And I am also the head of a associate of the Department of Astrophysics at the American Museum of Natural History. Both of them are in New York City. Welcome to take extra classes here.
Answer: learn something he was interested in
The author's sixth-grade teacher advised the author to _ .