Children who spend a lot of time playing video games do better at school, an international study has suggested. The Paris-based Organisation for Economic Co-operation and Development said there was strong evidence that playing computer games on handheld consoles like Nintendo DSs and Sony PSPs had 'positive effects on learning'. It said many games 'incorporate good learning principles' and can 'hone problem-solving skills'. The Paris-based Organisation for Economic Co-operation and Development said there was strong evidence that playing computer games had 'positive effects on learning' Girls are more likely to get higher marks at school because teachers like them more, an international report has found. Teachers consistently give better results to girls even when they perform similarly in international tests, the Organisation for Economic Co-operation and Development said. It suggests that teachers have a 'gender bias' towards girls because they are well behaved and listen in class. 'Girls' better marks may reflect the fact that they tend to be 'better students' than boys: they tend to do what is required and expected of them, thanks to better self-regulation skills, and they are more driven to excel in school,' the study says. But this may harm girls' future career prospects, the OECD suggests, because bosses  reward people based on what they  can do rather than their school grades. Students who play one-player video games between once a month and almost every day perform better in mathematics, reading, science and problem solving than students who hardly ever play games, the OECD said. But the evidence shows that playing computer games only helps children at school if they are not competing against other people over the internet. Boys are much more likely than girls to play computer games – but often get caught up in shoot 'em ups and other online competitions against other players, the study said. This means that playing on the computer at home helps girls more than boys. The report said: 'The gender gap in video gaming translates into a performance advantage for girls.' However, it also warns that the 'addictive nature of gaming' has its downsides. It said: 'Students who play video games excessively might not be able to focus on their work at school, may be less willing to spend time on school work at home, might develop sleep problems, and might be less perseverant if there are no immediate rewards for their efforts, like those offered in gaming.' Today's shock research comes after Boris Johnson claimed video games were helping children become 'nicer, kinder and more well-balanced' than their parents – and was even helping to cut crime. Students who play one-player video games between once a month and almost every day perform better in mathematics, reading, science and problem solving than students who hardly ever play games . The London Mayor ridiculed claims mobile phones and handheld games consoles were turning youngsters into 'lidless lizards'. Mr Johnson said he understood people's concerns when they saw their children 'bathed perpetually in the light of the screen gazing like lidless lizards at whatever depraved and corrupting material they can find'. But Mr Johnson said: 'I see no evidence whatever that tech is coarsening or depraving the young people of today. Boris Johnson has praised video games for making today's teenagers more sociable than their parents . 'In fact I would say that on the whole the younger generation are nicer, kinder, more well-balanced and more emotionally literate than my lot ever were.' The London Mayor added: 'And when you consider the very steep falls in crime that we are seeing not just in London but across the developed world and when you consider that crime is overwhelmingly committed by young men you have to wonder whether there is a correlation - a link between the tech boom and the rise in civility. 'What do they suffer from, the young men who are so foolish as to get sucked into crime? Anger, low self-esteem, a sense of social exclusion - a feeling that no one much cares about them. 'And what do they get from these gizmos – endless opportunities for self-expression, communication - the myriad pipette drops of self-affirmation that come with the selfie and the text and the shared video.' Today's OECD's report also warns against the growing divide between girls and boys in science and maths. It blames gender stereotypes and girls' lack of confidence for putting them off the core subjects. The report - using research from international tests in reading, maths and science to examine gender differences in education - argues that parents, teachers and employers all have ingrained 'biases' that they are passing on to youngsters. Across the 64 nations examined, women are much less likely to consider careers in science and maths-based subjects and to have the same self-confidence as boys in these areas. Overall, less than one in 20 girls considers working in science, technology, engineering and maths, compared to one in five boys, despite the sexes achieving similar results in international science tests.
OECD report finds computer games have 'positive effects on learning'
Many games 'incorporate good learning principles' and 'problem-solving'
Children who play   almost every day do better at maths and reading . But it warns there are downsides to the 'addictive nature of gaming'
Gaming can cause sleep problems and often stops children exercising .