TEENAGERS' mathematics and reading skills are in an unprecedented decline across dozens of countries and COVID school closures are only partly to be blamed, the OECD said in its latest survey of global learning standards. The Paris-based Organisation for Economic Cooperation and Development said it had seen some of the steepest drops in performance since 2000 when it began its usually triennial tests of 15-year-olds reading, maths and science skills. Nearly 700,000 youths took the two-hour test last year in the OECD's 38 mostly developed country members and 44-non members for the latest study, closely watched by policymakers as the…