The UK's teenagers are continuing to lag behind their peers in countries such as Singapore, Japan and tiny European nations when it comes to science, maths and reading, a major international report has found.
The study, published by the Organisation for Economic Co-operation and Development (OECD), assesses how students could use their knowledge and skills in real life, rather than just being able to repeat facts and figures parrot-fashion.
Although the UK performs above the OECD average in science and reading, it is more mediocre when it comes to maths.
It trails the likes of Estonia, Finland and Norway, according to the latest triennial Programme for International Student Assessment (Pisa). The report, across nearly 1,000 pages and two volumes, found Singapore was ahead in all subjects.
It found the UK spends about 114,900 US dollars (£90,284) per student from the age of six to 15 - more than the average across OECD countries of 90,300 US dollars (£70,954) and well above the 75,300 US dollars (£59,167) across all 72 countries included in the study with data available.
The UK came 15th for science, up from 21st, while it fell to 27th for maths, a drop of one place, and 22nd in reading, up from 23rd.
The study involved just over half a million 15-year-olds across the globe, with the two-hour tests including some multiple-choice answers.
In science, the UK's teenagers scored 509 points - down from last year's 514, but above the OECD average of 493. It put the country on a par with the likes of Germany and the Netherlands, slightly above Switzerland, Ireland and Belgium, but below New Zealand, Slovenia and Australia.
It means the country continues to trail leading nations including Singapore, Japan, Estonia, Chinese Taipei and Finland.
In reading, the UK's teenagers scored 498 points - down from last year's 499, but above the OECD average of 493. The results put the country level with Portugal, slightly above Chinese Taipei and the US, but below France and Belgium.
It means the country continues to trail leading nations including Singapore (with 535), as well as Hong Kong and Canada. Finland, in fourth, scored 526, one place above Ireland (521).
In maths, the UK's teenagers scored 492 points - down from last year's 494, and around the OECD average of 490. It put the country on a par with the likes of the Czech Republic and Portugal.
Singapore has a score of 564, ahead of Hong Kong and Macao.
OECD analysis found the average science, maths and reading performance of 15-year-olds in the UK had remained stable since 2006.
The Pisa tests are not without their criticisms - with some claiming the figures are less reliable for comparison as they do not take data from all schools, with most countries offering about 5% of their eligible 15-year-olds for testing.
Announcing a £12.1 million investment until 2019 to support the teaching of science in schools, schools standards minister Nick Gibb said: "We are determined to give all young people the world-class education they need to fulfil their potential. It is encouraging to see so many young people setting their ambitions high, as we know science is valued by employers and is linked to higher earnings.
"Studying science offers a wide range of options following school - whether that's a career in medicine, engineering or teaching science in the classroom, these are the vital skills needed for the future productivity and economic prosperity of this country.
"This extra funding will further support high-quality science teaching in our schools."
Shadow education secretary Angela Rayner said: "After six years of turmoil in our schools, we have not made the progress we were promised by the Tories.
"We were told that the constant chopping and changing would all be worth it to see our international standing in education shoot up the tables.
"But what the Tories have delivered instead is a crisis in teacher recruitment and retention, chaos in the exam system, class sizes rising and schools facing the biggest budget cuts in decades.
"The Tories are failing in education by their own measure. It is time they started paying attention to what really drives up standards in schools - excellent teaching and a good education for all children, not just the lucky few."