Teacher: 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.
Teacher: Now, understand the problem? If you are still confused, see the following example:
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 _ .
Reason: It is clearly mentioned in the article that to the check effect of mood on children is the main purpose of the experiment.

Now, solve this instance: Article: People who enjoy a dream-filled sleep are better at recalling information and making links between facts when they wake, scientists found. But recharging with a shallow nap offers no such mental improvement, the research suggests. The results of the study add to the evidence that Rapid Eye Movement (REM) sleep is very important to the brain's ability to strengthen memories. An average night's sleep includes four or five periods of REM sleep, but these tend to be longer towards the end of the night. This means that adults who get less than the recommended seven to eight hours a night -- and therefore inadequate REM sleep -- may be damaging their mind's ability to form strong memories. Although REM sleep is not classified as a type of deep sleep, it is only reached after the brain has passed through deep sleep stages. In the most recent study, participants were shown groups of three words -- such as "cookie", "heart", and "sixteen" -- and asked to find another word that can be associated with all three words. In this example, the answer would have been "sweet". They were tested once in the morning and then given the same task again in the afternoon. In between, some were allowed a nap with REM sleep, some a nap without REM sleep, while the others had a quiet rest period. The quiet rest and non-REM sleep groups showed no improvement in their test results, but the REM sleep group improved on their morning performance by an average of almost 40 percent. Dr Sara Mednick, a sleep researcher at the University of California who led the study, believes the formation of connections between previously unassociated information in the brain -- which leads to creative problem-solving -- is encouraged by mental changes which occur during REM sleep. People woken while their closed eyes made rapid movements recalled much more color1ful and detailed dreams than people woken during other stages of sleep.
Answer: sleep with four or five periods of REM
Student:
According to the passage, to have a good memory, a person had better _ at night.