Chemistry pupils have flunked O-level questions from 50 years ago, deepening fears that the subject is being dumbed down.
The teenagers were unable to answer questions from the 1960s and 1970s set by the Royal Society of Chemistry.
The average mark for the 1960s questions was just 16 per cent.
Focused: A 1960 chemistry class
Yesterday, the society warned that pupils are no longer tested in rigorous problem-solving and are instead guided to the right answers.
It said that modern exams use questions that require only one or two lines of working.
Even bright pupils were baffled by many of the old questions, said the RSC chief executive, Richard Pike.
He added: ‘There is no doubt that the clever pupils are as sharp as they ever were, but most are being stifled by an educational system that does not encourage more detailed problem-solving and rigorous thinking.’
Two thousand 16-year-olds from 450 schools entered the online competition, which involved sitting a two-hour paper made up of chemistry O-levels and GCSEs from the past five decades.
Test your chemistry knowledge: Can you answer these?