College lecturers are often delighted if they manage to hold the attention of students for a two-hour period without their audience falling asleep.
Imagine then trying to teach a group of 60 students non-stop for three days and nights, without you or them taking a wink of sleep.
That is the feat achieved by Sanjay Kumar Sinha, a college lecturer Mumbai, India, in an attempt to get into the Guinness Book of Records for delivering the world's longest lesson.
He taught for 73 hours and 24 minutes, overtaking the current record held by Elzbieta Malinowska from Poland, who taught for 66 hours in June 2004.
"I have a craze for teaching grammar and am still charged up. I devised my own teaching method for this event which is very interactive," said Kumar Sinha He used a mixture of visual, auditory and kinaesthetic methods in his attempt to keep his sleepy audience awake, asking them to read out sentences, shout out answers, respond to queries and generally engage them by throwing questions at them.
He got them to dance, to do yoga and gave them breathing exercises to stimulate their minds and get back to focusing on the lesson.
Some 72 students were initially chosen to participate in the event, but 12 dropped out during the three days for medical reasons such as low blood pressure and vomiting or because they fell asleep.
A medical team was kept on watch for any emergency. Their diet was strictly monitored and they were given salads, juices and boiled food to help keep sleep away.
The whole three-day lesson was recorded and the tapes are to be sent to Guinness officials for approval.
Mr Sinha already features in Indian record books for teaching the fastest lesson - designed to promote quick learning techniques he has devised.