New techniques for teaching maths are being imported into English primary schools from China, which ranks first in the world in the subject. Isabel de Bertodano speaks to those at the forefront of change Katrina Hassan, a maths teacher from London, went to observe lessons in Shanghai, and the first thing that struck her was how much time the teachers had on their hands.“They only teach one subject, their lessons are 35 minutes long and they teach two or three classes a day,” she said. “Our lessons last an hour and maths is just one of the many subjects we teach throughout the day.”Hassan, who teaches at St Vincent’s Catholic Primary in Marylebone, central London, was one of a large cohort of teachers taking part in the new Shanghai Teacher Exchange programme