Too many of England’s schools are entering pupils for the math General Certificate of Secondary Education (GCSE) early, says the Office for Standards in Education, Children’s Services, and Skills (OFSTED) in a major report that is critical of the way the subject is taught and tested. The process is preventing too many able pupils from fulfilling their potential, says chief inspector Sir Michael Wilshaw–and many who get off to a poor start never catch up, he warns.

The report, Mathematics: Made to Measure, also says that math exams have become less demanding and that teaching standards vary unacceptably. In the report: Wilshaw warns that “the extensive use of early GCSE entry puts too much emphasis on attaining a grade C,” which is the benchmark grade used for schools’ headline league table measures.