Chris Cramer didn’t sleep much last semester. The chemistry professor and four other University of Minnesota professors are volunteering hundreds of hours to teach free massive open online courses this summer, the Minnesota Daily reports. MOOCs are open to an unlimited number of people from anywhere in the world who have access to the Internet, and the University’s MOOCs have drawn anywhere from about 8,000 to more than 16,000 students so far. “I’ve probably put 400 hours into preparation,” said Cramer, whose course started May 20. “That’s a lot of time.” Cramer isn’t the only one logging long hours on his MOOC. Assistant professor Jason Hill pushed his Sustainability of Food Systems class back from what was originally a May start date to mid-June because he needed more time to work on his lecture videos. Hill taped interviews between him and other professors at the University for his class videos, which he said could help to create more interest in MOOCs at the University for the future.