Jo Boaler, a professor of mathematics education at Stanford University, is not new to criticism of her work turning ugly. Boaler champions a reformist approach to teaching maths, arguing that strategies that emphasise reasoning over memorisation lead to more equitable outcomes. When she first moved to the US from Britain in the late 1990s, she was warned that her research would anger defenders of traditional methods. Backlash from some colleagues – including accusations of “scientific misconduct” that the university dismissed – grew so personal that she briefly moved back to the UK. Back at Stanford two decades later, Boaler was...