Roger Taylor tells MPs it was a “fundamental mistake” to believe the public would accept results decided by an algorithm.
Thousands of students were downgraded before the government and exams watchdog were forced to U-turn over the issue.
Education secretary had tried to shift blame for the exams fiasco, which saw mass downgrading of students.
There has been fury among MPs and pupils after Ofqual guidance on appeals in England was suddenly withdrawn without explanation.
Students across the country have been thrown into further "unacceptable" chaos by the sudden withdrawal of appeal guidelines.
A former children's minister said the “extraordinarily distressing" results may be unfair.
Nearly 40% of estimated grades were downgraded.
Nearly 40% of UK grades are expected to be lowered by a “biased” algorithm.
In June 2017, students in England sat the new 9-1 maths GCSE papers for the first time. The change was more than a simple
A*-G grades are being scrapped for a numbered grading system.
Changes to how GCSEs are graded will put more pressure on students and could limit their opportunities, teachers have warned
Traditional academic subjects have seen a rise in A-level and GCSE popularity this summer, with maths, English and the sciences
Last week's furore with one of the maths GCSE papers raised some interesting points. There were a number of difficult questions including the now infamous one referred to as the Hannah's sweets question..
Dozens of GCSEs, AS and A-levels are set to be ditched in the latest stage of a major shake-up of exams. Courses in subjects
England's exams watchdog has expressed "serious concerns" about the standard of some qualifications being offered to foreign
GCSE grades will be scrapped and replaced with a numbered scale with coursework being removed completely from some subjects
The number of top GCSE grades has fallen for the second year in a row, after a drastic - and controversial - upheaval of
Schools are entering teenagers for GCSEs early, or multiple times, in order to secure good grades, the regulator has warned
Students are re-sitting their GCSE exams up to seven times so their school can improve its ranking on national league tables
Ofqual has warned to expect a drop in GCSE science grades after changes in the syllabus, which have "completely confused