Teacher: In this task, you're given an article and an answer. Your task is to generate the question for the answer based on the given article.
Teacher: Now, understand the problem? If you are still confused, see the following example:
Article: There are a lot of public libraries in Britain. These libraries have more than one hundred and fifteen million books, not including those libraries of public schools. Public libraries not only lend books, music records but also help children, patients in hospitals and others to get special play readings, film shows and so on. The first public libraries were founded in about the year 1850. Today's public libraries usually have a reading-room, a lending room and a reference room. The greatest and most famous library in Britain is that of the British Library in London. It was founded in 1973 and has over 10, 000, 000 books. It has nearly every magazine, newspaper and book published in Britain and other parts across the world.
Answer: 10,000,000 or less.
Solution: How many books are there in the British Library?
Reason: In the Article, 10,000,000 is mentioned for the number of books available in the British Library, so this is a good question.

Now, solve this instance: Article: It's hard to avoid looking like a fool on April Fool's Day. On April 1 each year, people play tricks on each other. These tricks are usually silly rather than mean. Classmates sometimes tie each other's shoelaces to their chairs.Teachers might hand out an impossibly difficult surprise test that scares students before they realize it's only a joke. Newspapers announce fake contests (such as "Win an elephant!") and report on fake stories (like "UFO" lands in New York City). Forget gifts, songs and special foods--those are for the other holidays of the year. On April Fool's Day, the only tradition is to laugh (and maybe to cause a little bit of trouble). One April Fool's Day, when I was in high school, a group of students in my class played a very clever and funny trick on the teachers. They bought some chickens and set them free in our school cafeteria. The chickens ran all round the school, in and out of classrooms and under our feet. Feathers were flying everywhere. Teachers began running after the chickens, trying to catch them. Finally, they caught four of them. But the chickens were wearing numbered tags around their necks, and the teachers discovered that they had only caught chickens No.1, 2, 3, and 5.Where was chicken No.4? The teachers looked and looked. They couldn't find another chicken. After a few hours, they realized that the students had played another joke on them: There were only four chickens in the first place! They've been tricked by the numbers on the chickens. It's been a long time since I was in high school, but that April Fool's Day remains one of my favorite memories from those years.
Answer: They wanted to play a trick on teachers.
Student:
Why did students set chickens free?