A third of schools in Wales are not up to scratch, according to inspection body Estyn.
A report produced by the organisation noted that improvement is "slow" in many schools, the BBC reports.
Estyn chief inspector Ann Keane said Welsh schools must "face the facts" and "raise standards relative to other countries".
It was revealed that 40 per cent of pupils beginning secondary school had a reading age below their actual age.
"Teachers and leaders need more training in how they deliver literacy and numeracy, not just in English and Welsh lessons but across the whole curriculum," Ms Keane said.
"That doesn't just mean that basic skills are not being taught well enough, but that we're not delivering in the higher order skills of literacy and numeracy either."
Only eight per cent of schools in Wales received a top rating from Estyn inspectors.
Welsh education minister Leighton Andrews earlier this year called for a debate about the future of a-level and vocational subjects in Wales, adding that it is important that young people have the right qualifications to succeed in the workplace.
Posted by Dolcie Thacker