In 2015, the OECD published The ABC of Gender Equality in Education, one of the first major international studies to highlight a consistent pattern in classroom assessment: when teacher grading was compared against standardized external tests, boys systematically received lower marks than girls, even when their performance was identical [1]. Teachers "generally award girls higher marks than boys," the report stated, especially in the language of instruction. The OECD flagged this as a hidden...