It was while watching his 10-year-old son in class one day that T. Mills Kelly thought of a new way to teach history to undergraduates at George Mason University in Virginia.

Asked to answer questions about the American Civil War, the children ¡°threw themselves down on the floor, got out their coloured pencils and formed themselves into groups¡±, Professor Kelly said.

He lamented that none of his students were so engaged with the subject. ¡°They enjoy being history majors, but they¡¯re not having fun being history majors,¡± he thought.

He had to find a way to make the subject more fun.

Although Professor Kelly, a former fellow at the Carnegie Foundation for the Advancement of Teaching and associate director of George Mason¡¯s Center for History and New Media, had long looked for ¡°disruptive¡± ways to teach history, few ideas were as disruptive as the one he had that day: get his students to make things up.

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In a course titled Lying About the Past, Professor Kelly encourages students to create elaborate hoaxes based on fact. He said it was an ideal way to teach historical method - and to instil the kind of scepticism historians need but undergraduates increasingly lack.

¡°If I had told my students four years ago that to complete the final assignment for this course, you¡¯re going to have to work in a group, learn video production, go to the Library of Congress, manipulate images - if I had told them all of this, they would have dropped the class or told me long sob stories about how they had a job or were on a sports team and couldn¡¯t possibly do all these extra things,¡± Professor Kelly said.

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¡°But instead I told them: ¡®You have to create a hoax.¡¯ I have never had a group of students work so hard.¡±

One reason, he said, was because students ¡°laughed their way through the whole semester¡±, but another was the fact that the internet was central to the idea.

¡°All the research on people under 30 right now points to the fact that the internet for them is not just a resource: it¡¯s a place of creation,¡± he said.

Dread pirates and serial killers

The first hoax created by the class involved ¡°Edward Owens¡±, a pirate who attacked shipping off the US East Coast in the late 19th century but had been forgotten until undergraduate ¡°Jane Browning¡± (also part of the hoax) stumbled across his story.

Owens became the subject of a Wikipedia entry, and the student blogged about him and posted a YouTube video of herself visiting the site of his house and interviewing historians about him. Soon the story started making the rounds on Facebook and Twitter, and appeared in the national newspaper USA Today.

Another hoax cast light on ¡°Joe Scafe¡±, a 19th-century serial killer in New York.

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A third disclosed the long-lost recipe for ale from the Baltimore brewery where the most famous American flag was sewn during the War of 1812 - the flag that became the subject of US national anthem The Star-Spangled Banner.

All the tales were built on fact.

At the time Scafe was purportedly active, four women were killed in the same manner in New York. The students researched the real victims and other details in the National Archives and elsewhere, and created authentic and factual Wikipedia entries about them. But the rest was fiction.

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Professor Kelly¡¯s students got away with their pirate story for a while before finally admitting themselves that it was fake.

But many who were duped were not amused. Jimmy Wales, Wikipedia¡¯s founder, called the ruse ¡°annoying¡±.

Professor Kelly said that responses were equally divided between people who approved of his methods and those who disliked them - in one case, strongly enough to send him a death threat that he referred to the university police.

He maintained that the class was effective.

¡°They¡¯re not going to forget these lessons,¡± he said. ¡°For the rest of their lives they are going to maintain this level of scepticism.¡±

And so might many readers. The hoax about the New York City killer was debunked 26 minutes after it was posted on the website Reddit, whose members pieced together the fact that the Wikipedia entries about the victims were new and had been written by users who were newly registered.

No matter, said Professor Kelly, whose course has garnered international attention.

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¡°All around the world, hundreds of thousands of people are thinking about these issues, even if for only 30 seconds,¡± he said. ¡°And they¡¯re also thinking about how history should be taught.¡±