"Why," asked one questioner, "do you keep writing about the Tiananmen Square incident and the Cultural Revolution? The past is the past. China has changed. It is time to move on."
He had a point. The world's most populous nation has indeed been transformed in many ways since the dark days of Mao Zedong and the massacre of civilians by the People's Liberation Army in1989. But the same could also be said of Japan since the second world war, yet many of the students had a very different view about the value of history when it came to the atrocities committed by their neighbour more than half a century ago.
"Why," asked another questioner, referring to the massacre in Nanjing in 1937 and the imperial army's use of sex slaves, "can't Japan face up to the past?"
Such double standards are, of course, not limited to China. Nor does everyone in Beijing accept that Tokyo has a greater responsibility to grapple with unpleasant past episodes than their own government.
Yet the events of the past six months suggest that the education and media systems in China are exacerbating knee-jerk nationalism and choking critical self-reflection in a way that augurs badly for the country's bid to become a world leader in ideas as well as exports.
In April and May, more Chinese protesters took to the streets than at any time since the Tiananmen Square protests of 1989. Instead of marching for democracy, however, they were rallying against Japan. The ostensible prompt for the demonstrations was Tokyo's approval of a new history textbook that whitewashes the darkest moments in Japan's past.
It is not hard to see why the new book - produced by the right-wing Japanese Society for History Textbook Reform - stirs up anger. It makes no mention of the Japanese army's use of "comfort women" sex slaves and biological warfare unit 731's deadly experiments on prisoners and unsuspecting villages.
It also casts doubt on the judgment by the Tokyo war crimes tribunal that hundreds of thousands of civilians were massacred in Nanjing. Claims that "many" people were killed in 1937 "are still being debated" today, it says.
Although the book is shunned by the vast majority of Japanese schools, the very approval of such a text is seen as an insult in China and South Korea.
Repeated Japanese government apologies are also undermined by prime minister Junichiro Koizumi's annual visits to Yasukuni shrine, which has a museum glorifying the country's invasion of Asia as a heroic battle against western colonialism, downplaying the wrongdoing of war criminals and insisting the emperor never renounced his divinity.
Yet at least there is a public debate in Japan about such issues. Mainstream newspapers such as the Asahi Shimbun are sharply critical of Mr Koizumi's visits. Left-leaning weekly magazines and the communist newspaper "Akahata" are legally free to publish criticism of the government's failure to face up to the past.
On the anniversary of the end of the war every August, pacifist demonstrators are able to protest outside Yasukuni even as war veterans and ultra-right gangs honour the fallen soldiers enshrined inside.
There are unofficial restrictions on the media in Japan. Many newspapers self-censor negative reports about the emperor. Gangs of nationalist thugs attempt their own form of control through intimidation, with sometimes murderous attacks on left-wing journalists and cinemas that show pro-China films about the Nanjing massacre or unit 731.
But this is nothing compared to the systematic government blocks on historical debate in China, where schoolbooks ignore or gloss over the famines of the Great Leap Forward and claim that it was Mao Zedong's communists - rather than American nuclear bombs - that defeated Japan in 1945. Most texts make no mention at all of China's failed attack on Vietnam in 1979.
In the media and higher levels of academia there is some discussion of more contentious aspects of history, such as the struggle with Taiwan, the invasion/liberation of Tibet and the chaos of the Cultural Revolution, but nothing like the range of opinion to be found in Japan, where some scholars and journalists are brave enough to say - and write - heretical truths about the emperor, such as that he is descended from Korean stock.
The tale of the two massacres is revealing. In Japan, the extent of the killings in Nanjing almost 70 years ago has been the subject of countless documentaries, symposiums and books. In China, discussion of the killings in Tiananmen 16 years ago is entirely taboo. A search on the English language website of Xinhua - the Chinese state news agency - over the past month showed 30 articles relating to the Nanjing "massacre" and only one that referred to Tiananmen, which was described as an "incident".
Of course, there are important differences between the two. As well as the vastly different scale and temporal distance, the crimes of Nanjing have been judged by an international jury (albeit one comprised mainly of its former enemies during the Tokyo war tribunal), while the rights and wrongs of Tiananmen have never been assessed in any meaningful legal and public fashion. In other words, Japan has been found guilty and a right-wing minority is now trying to lodge an appeal in the court of domestic and world opinion. China's communist party, however, believes it has no reason to stand trial.
Some would argue that this is a justifiable position because Tiananmen was a domestic issue, while Nanjing was a violation by a foreign power. But in terms of morality or historical truth, does this really matter? In both cases, soldiers slaughtered civilians. The questions of how many and why ought to be debated - and not only by those responsible for giving the orders.
Refreshingly, the students in Beijing were free to discuss any subject. And they were as critical of the "overly positive" domestic media as they were of the "excessively negative" foreign correspondents. It would be as wrong to assume that they all want to ignore Tiananmen and the Cultural Revolution as it would be to claim that the majority of Japanese support Koizumi's visits to Yasukuni.
Compared to 25 years ago, China is more open, but there is still a knowledge gap between the two countries that reflects badly on Beijing. Students in Tokyo (or London for that matter) are taught a sanitised version of their nation's history, but at least they can read an alternative view in the domestic media. Such is the degree of censorship in China, however, that some of their counterparts in Beijing admit sadly that they have to rely on overseas reports.
"I never knew before about the Tiananmen killings," one student told me. "At first I didn't want to believe it. But I checked everything I could find on the internet and now I think it's true. It is a shame that we have to learn about what is going on in our own country from foreigners."