A new YouTube clip has been circulating this week and is destined to take its place along with that other amateur classic, the 'bus uncle' episode, for its violence and profanities. But, ironically, it may shed some light on why our students consistently score better in maths and science than their counterparts in the west. Judging from viewers' comments on the website, it seems some think the 28-second clip was staged; others believe it's another instance of classroom violence. We think it proves something else. The opening has what appears to be three senior secondary school students bending over a maths exercise book in a classroom. Two of them start to argue over a solution and curse each other. Most of the dialogue cannot be translated because this is a family newspaper, but the gist is that the two could not agree on whether the solution involved 2x or -2x. Here is an abridged and sanitised version of the exchange: 'You unintelligent being. It's obvious even to your mother's modesty that it's 2x. It's so xxxxx obvious.' 'You drop-dead fool! Of course not - there is still -2x to worry about!' The two then come to blows. If the clip is fake, I say the kids have a seriously offbeat sense of humour worthy of comic actor Stephen Chow Sing-chi. But if it's real, no wonder our children are staying ahead when they invest so much energy and pride in getting their maths right.