Adults are not schoolchildren and – as all good teachers know – you’re deluding yourself if you pretend to be one of the kids. Oscar Murillo, best known as one of the four artists who chose to share the 2019 Turner prize, has ignored that wisdom. He has returned to his former school and to his adolescence. After his family came from Colombia to Britain when he was 10, he was educated at Cardinal Pole Catholic School in Hackney, east London. It is an impressive place. Indeed the evident seriousness of the school – and the articulacy of its senior pupils, who are spending the summer as helpers for the project’s producers Artangel – oddly shows up the bad-boy fantasy of Murillo’s project. Apparently Murillo was unhappy, frustrated and rebellious at school. He sees the same alienation in the pen marks and cuts pupils everywhere leave on their desks. So, since 2014, he has been providing school classes across the world with pieces of canvas to graffiti as they wish, assembling a global archive of dissident art made by 10 to 16-year-old kids at 350 high schools in 30 countries. In his installation of this entire hoard in Cardinal Pole’s hall, the boredom of a planet of adolescents seeps from thousands of inky doodles. A rotating selection is displayed on glass-covered tables while the rest are stacked on shelves in a well-organised archive to be consulted with the help of volunteers, as if you were in a library researching a PhD on the teenage mind. It is immediately disappointing. I was hoping for wild visual chaos, but the display is curiously academic. The selection on tables invites quite a dry, studious kind of looking. And then the problems really start, because what are you looking for? Art? Some kids have drawn hearts and written the word Marvel, or declared love for a boy or girl, or scribbled “Shawn Mendes”. Others have done really good cartoons of sharks and superheroes. Then you notice one wit has written “El Barto”, the graffiti tag of Bart Simpson. This is telling. For it’s very self-conscious, isn’t it? The student clearly had Murillo’s number. That’s the thing with kids, they see through grownups. It’s a parodic response, perhaps by a child who has no interest in asinine doodles or adult-sanctioned rebellion. Murillo wants them all to be Barts. What if they’d rather be Lisa? Others have rebelled by doing actual art. The most rewarding way to explore Murillo’s archive is to let students from Cardinal Pole help you consult the stacks of canvases in depth. Arbitrarily I chose a pile from Italy, and it looked as if the schools there had cunningly let their most talented artists dominate the project. Either that or there’s a glut of natural ability in the land of Leonardo and Michelangelo. One student has even done a Leonardo-like drawing of a horse, in perspective. Another has not simply depicted brightly coloured balloons but given them white highlights that deepen their circular forms – another display of artistic skill that goes against the chaotic street-art dissonance of the artworks seen en masse. This is the thing Murillo’s cult of the adolescent sulker forgets: school pupils are not a mass of identical stereotypes. They are individuals, with abilities and talents and potential. Those accomplished young Italian artists don’t want to scribble, they want to draw well. So why waste their time on entertaining adults for whom this is the very latest in cool outsider art? Going into a British school at the start of the summer holidays, after the disruption of two educational years by the pandemic, and as the parent of a 16-year-old, it is disturbing to see an exhibition that views teenagers as some undifferentiated delinquent mass. The entire problem with the way we see the young, as a society, is that we fail to discern their individuality. In the end, I found I was more interested in talking to pupils than wading through adult-commissioned adolescent imagery. Murillo is caricaturing adolescence to suit his own memories, which are probably as edited as yours and mine. The final insult to The Kids is also the best reason to visit this exhibition. At intervals along the shelving stacks are big paintings by Murillo himself: strong, beautiful, blue abstractions daubed on top of schoolkids’ doodles. The art he has made out of his encounter with global teenagedom is bold and confident, and of course highly skilled. The joke’s on him – he’s a role model for individual achievement. No wonder his old school is proud.