You will be given a definition of a task first, then an example. Follow the example to solve a new instance of the task.
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: Homework can put you in a badmood , and that might actually be a good thing. Researchers from the University of Plymouth in England doubted whether mood might affect the way kids learn. To find out the answer, they did two experiments with children. The first experiment tested 30 kids. Someshapes were hidden inside a different, larger picture. The kids had to find the small shapes while sitting in a room with either cheerful or sad music playing in the background. To test their mood, the scientists asked the kids to point to one of five faces, from happy to sad. Children who listened to cheerful music tended to point to the smiley faces while the others pointed to the unhappy ones. The researchers found that sad kids took at least a second less to find the small shapes. They also found an average of three or four more shapes. In the second experiment, 61 children watched one of two scenes from a film. One scene was happy, and the other was sad. Just like in the first experiment, kids who saw the sad scene acted better compared to the others. The researchers guessed that feeling down makes people more likely to focus on a problem or difficult situation. Not all scientists agree with them, however. Other studies argued that maybe, that cheerful music in the first experiment distracted kids from finding shapes. While scientists work on finding out the answers, it still might be wise to choose when to do your tasks according to your mood. After eating a delicious ice cream, for example, write an essay.
Answer: whether mood affects their learning ability
Solution: Researchers did experiments on kids in order to find out _ .
Why? It is clearly mentioned in the article that to the check effect of mood on children is the main purpose of the experiment.

New input: Article: April Fools' Day, not officially considered a holiday, is most definitely a notable day that is celebrated in many countries on April 1. The thing that is so special about April 1 is that it is the day for playing tricks and practical jokes on others. The aim of these jokes is to bring embarrassment to others. Superstitions have it that the practical jokes are meant to be played before noon, and that those that are performed afterwards will bring bad luck. This limitation is widely losing its value due to the fact that many major hoaxes throughout history appear after noon. Another superstition is that anyone who fails to respond properly to the jokes played on them is also said to be easy to suffer from bad luck. Some people think that being fooled by a pretty girl will be accompanied by marriage, or at least a friendship with her. That sounds like a good deal if she is truly pretty. Some people believe that being married on April Fools' Day is not a good idea for a man, and that forever in the future he will be ruled by his wife. The origin of April Fools' day is not clearly known, but it is generally accepted to have come about as a result of the changes in the calendar system. The New Year celebrations used to begin on 25 March and last for a week, ending on 1 April. In 1582, Charles IX, King of France brought in the new Gregorian calendar, in which the new year began on 1 January. Unfortunately, some people did not hear about the change, and many others simply refused to break the tradition.
Answer: jokes can be played on this day
Solution:
April Fools' Day is different from other festivals probably because _ .