Some students taking free classes from?Coursera may never know the right answers.

A University of Michigan professor teaching one of the company¡¯s massive open online courses told students this week he could not provide them with correct answers to questions they get wrong because doing so would reduce efficiency. ?

The professor¡¯s decision is prompting additional questions by critics of Moocs about their ability to provide quality teaching.

Michigan professor Gautam Kaul is teaching the Introduction to Finance Mooc on Coursera. In a July 2 email to students, Kaul said students wanted to know correct answers to assignments but he would not oblige their requests.?This means some?Coursera?users who get a question wrong could be left in the dark.

É«ºÐÖ±²¥

He called the students¡¯ request for correct answers ¡°reasonable¡± but ¡°very difficult to accommodate¡±.

¡°If this were a one-time class, we would have considered posting answers,¡± he wrote in an email that was provided to?Inside Higher Ed?by a critic of Moocs. ¡°It will however be very difficult for us to offer this class again if we have to keep preparing new sets of questions with multiple versions to allow you to attempt each one more than once. Handing out answers will force us to do that.¡±

É«ºÐÖ±²¥

Professor Kaul did not respond to a July 3 email seeking comment.

Some Moocs, in fact, do allow students to see the right answers to questions they get wrong. But Coursera leaves the decision up to the universities and professors that offer courses on its platform, said Andrew Ng, the Stanford University professor who co-founded Coursera.

¡°Most Coursera courses do share the answers, though Professor Gautam chose not to do so, in order to make cheating harder in subsequent offerings using the same questions,¡± he said via email through a spokeswoman.

¡°Our platform provides several different options for creating highly randomised questions, which has allowed some instructors to feel more comfortable sharing the answers.?

É«ºÐÖ±²¥

¡°But ultimately it¡¯s up to universities to decide what they think works best for serving students in not just a single - but in repeated - offerings of a class.¡±

Jonathan Rees, a history professor at Colorado State University, Pueblo who has been critical of Moocs, said Professor Kaul¡¯s email suggested Moocs are meant to be frozen in time.

¡°What if the scholarship changes? What if you decide something doesn¡¯t work as well as it should? What if the students change? Tough luck,¡±?Professor Rees wrote on this blog. ¡°They get what they pay for.¡±