The evidence in favour of charter schools in America has strengthened

IMPROVING SCHOOLS is hard. Evidence of success or failure can take a decade to collect. What works in one place may flop in another. This explains why are excited about an authoritative study from Stanford University which shows that children learn. That should settle an argument over how to arrange America’s schools that has been raging for 30 years.The theory underpinning charters is that schools should be freed from the bureaucracy of the public-schools system and be able to hire and fire teachers based on merit. If they have these freedoms and are held accountable, then the benefits will show up in better results. That idea attracted Republican support, but it was controversial on the left. Although technocratic-minded Democrats, such as Bill Clinton and Barack Obama, supported charters, teachers’ unions opposed them, arguing that they drew resources away from other public schools. When charters succeeded, the unions said, it was only because they attracted the brightest pupils or the most motivated parents.