3. Passage Twenty-SevenOut of all the students who enroll in a massive open online course (MOOC)， only about 5 percent complete the course and receive a certificate of accomplishment.This statistic is often cited as evidence that MOOCs are fatally flawed (有缺陷的)and offer little educational value to most students.Yet more than 80 percent of students who fill out a post-course survey say they met their primary objective.How do we look at these two facts? We’re used to focusing on completion rates in higher education， but they’re not the only—or even the most meaningful—indicator of engagement in open online courses.With no cost to enroll， no punishment for dropping out， and little reward for actually earning a certificate， MOOCs are fundamentally different from traditional classes—and students use them in fundamentally different ways.Data from more than 1.8 million students enrolled in 36 MOOCs offered by the University of Pennsylvania show that students treat MOOCs like a buffet (自助餐)， sampling the material according to their interests and career goals.Some are curious about the subject matter and just watch one or two video lectures; others use the discussion forums to connect with their intellectual peers around the world.Of all enrolled students， nearly 60 percent watch at least one video， complete at least one assignment， or post at least once in a forum.So focusing on the tiny fraction of students who complete a MOOC is misguided.The more important number is the 60 percent engagement rate.Students may not finish a MOOC with a certificate of accomplishment， but the courses nonetheless meet the educational goals of millions.According to Para.3， students choose MOOCs for the following reasons EXCEPT ().