Even before the covid-19 pandemic ejected millions of children from their classrooms, schools across America were stuck in a rut. For 50 years the country has tracked pupils’ performance in maths and reading through its National Assessment of Educational Progress, a series of reference tests that are sometimes referred to as the “Nation’s Report Card”. For most of those five decades, scores kept improving. But they reached a plateau in the early 2010s. By 2020 test scores had started edging down.