Ofsted chief inspector Amanda Spielman is set to announce a major investigation into whether schools are delivering a broad curriculum amid a gaming “scandal”.

Spielman will tell Association of School and College Leaders (ASCL) conference delegates later today a conflict has emerged between a head’s desire to give pupils the right education, and to improve their league table position.

She will say: “We know that there are some schools that are narrowing the curriculum, using qualifications inappropriately, and moving out pupils who would drag down results.

“That is nothing short of a scandal. Childhood isn’t deferrable; young people get one opportunity to learn in school; and we owe it to them make sure they all get an education that is broad, rich and deep.”

That is nothing short of a scandal.

The move follows extensive investigations into gaming by Schools Week – including revealing how some school leaders were being urged to enter vulnerable pupils into a qualification that could be “taught in three days”, but was worth the equivalent of a GCSE.

The government announced last month that the qualification in question, the European Computer Driving Licence (ECDL) qualification, will now be removed from league tables.

Ofsted told its inspectors earlier this month to crack down on schools found to be gaming the system – which included entering whole cohorts of pupils into subjects with over-lapping content.

A year-long investigation by Schools Week last year also found that schools shifting large numbers of pupils to alternative qualifications were taking a gamble with their whole school results.

The investigation was based on an extensive study by Ofqual, chaired by Spielman at the time, that found the only school-led factor linked to swings in GCSE pass rates was the stability of a school’s exam entry profile.

Spielman will make it clear during her key note speech later today that she does not believe the curriculum has received enough attention during inspections in recent years.

“There is more to a good education than league tables. Vitally important though a school’s examination results are, we must not allow curricula to be driven just by SATs, GCSEs and A-Levels. It is the substance of education that ultimately creates and changes life chances, not grade stickers from exams.

“So I am determined to make sure that the curriculum receives the proper focus it deserves.”

The watchdog will investigate how maintained schools translate the national curriculum into effective classroom teaching, and how academies design their own curriculum.

The study will include looking at examples of the most successful curricula – across early years, primary, secondary, sixth and FE colleges – Ofsted has said.

Spielman’s curriculum experience to date includes her work as a senior advisor to the Ark Schools academy chain, known to favour a more traditional curriculum.

That includes the Mathematics Mastery approach, which involves whole-class teaching, taking pupils of all abilities through calculations in detail, and is supported by the use of high-quality textbooks.

The Ofsted study will also consider what can be done to tackle issues such as schools “curriculum narrowing”, and promoting social mobility.

Inspectors will carry out fieldwork over the coming months, with a final report published later this year.