When some low-achieving teenagers were kitted out in tank tops and gingham dresses and sent to a 1960s secondary modern, disaster beckoned.

The students on Channel 4‘s That’ll Teach ‘Em had difficulties adapting to the strict rules at the fictional Hope Green school. The girls railed that it was sexist they should learn to cook and clean while some of the boys appeared terrified of touching the school’s goats in rural science lessons.

But teachers who took part in the reality television series say that next week’s final episode will prove the experiment a success - and it is not simply pupils’ skills at chicken-plucking and changing tyres that have improved.

Jeanette Gibson, the school’s fierce English teacher, was surprised at the ignorance of some pupils, all predicted Cs, Ds or lower at GCSE. In one episode she had to argue with a pupil who insisted that tongue was spelled “tougue”.

However, Ms Gibson said the students did “surprisingly well” in a 1960s-style CSE English exam.

Only two pupils gained a grade one, then considered equivalent to an O-level pass. But around three- quarters received grades above a four, the national average in the 1960s. “It was a real eye-opener,” Ms Gibson said.

“I never realised how much children could change in such a short space of time.”

Richard Fawcett, the headteacher, said the pupils’ enjoyment of vocational lessons such as woodwork, in which nearly all the boys gained certificates, had knock-on effects on other subjects.

The former president of the Secondary Heads Association said: “I was forcibly struck by the motivating effect of the vocational subjects. It raises important questions about whether there is too little emphasis on practical skills, and too much on the academic, in vocational courses today.” This view is shared by the history teacher, Francis Peacock, though he believes the show may have slightly overstated the case for old-fashioned vocational courses.

“Part of it was the novelty - I’m not sure the pupils would have been so excited about bricklaying if they’d done it for two or three years,” he said.

Cornelia Welham, typing mistress, said the highlight for her had been seeing a pupil reach 11 words a minute on an antique typewriter. Sarah, who is dyslexic, had broken down in tears during the first typing lesson.

As well as revealing the pupils’ exam results, the final episode will show how they performed in an IQ test and see the girls rebelling against 1960s sexism during a Girl Guide and Scouts camp.

Ms Gibson said that her stern TV appearance had meant that more pupils at her real school, Windsor Boys, were calling her “Hitler”. “My poor Year 9 pupils had not met me until this week, but some had seen the series and were terrified,” she said.

That’ll Teach ‘Em is on Channel 4 on Tuesday at 9pm