The words "basically" and "like" are among words that are now forbidden in a slang ban at a London secondary school.

       Ark All Saints academy in Camberwell, south east London, has produced a list of terms and phrases pupils should no longer use in the classroom in a bid to prepare them for the more formal tone required for exams and the job market.

       Among the banned list are "basically", "like" and "you know", which are frequently used by teenagers at the beginning of sentences. Exclamations such as "oh my days" and "oh my god" are off limits. In addition, "that's long" (meaning boring or tedious) is prohibited.

       Teachers said the new rule was needed because these colloquial phrases were not only being used among friends in classrooms and playgrounds, but are also appearing in pupils' written work.

       Students can struggle to drop colloqialisms in exams

       Concerns were raised that if these language features were allowed to take root, pupils would struggle to express themselves succinctly when answering exam questions, and would be ill-equipped to deal with the more formal tone required in university applications and job interviews.

       Lucy Frame, the principal at the school, said: “The development of reading and speaking skills is a central part of what drives our school to help our students learn effectively and fulfil their potential in academic and non-academic ways.

       “None of the words or phrases listed are banned from general use in our school or when our students are interacting socially. But, this list is used in some formal learning settings to help students understand the importance of expressing themselves clearly and accurately, not least through written language in examinations.”

       Some of the phrases prohibited in formal contexts at school are likely to have crept into pupils' vocabulary due to being widely used in literature and music.

       "Oh my days" (meaning "oh my goodness"), which appears on the banned list, features in lyrics by the rapper Stormzy. "He cut his eyes at me", which means someone gives a withering glance, is used by writers including Lily Anderson and Richard Ford.

       'Unnecessarily rude and strident vocabulary'

       External examiners have noted that answers which are marked down in papers can sometimes be penalised because they include "unnecessarily rude and strident vocabulary".

       In 2019, a survey of more than 2,000 tutors found that the use of slang English was the most common reason for English GCSE failures.

       St Thomas Aquinas Catholic School in Birmingham has also made attempts to clamp down on informal language creeping into written work.

       It is encouraging pupils to avoid colloquialisms such as "like" and "so", and instead urging them to use "furthermore", "consequently" and "in conclusion" to link sentences and express arguments.

       However, some academics have argued that pointing out flawed or highly informal use of English could alienate teenagers who are merely trying to express themselves.

       Dr Natalie Sharpling, who teaches applied linguistics at Warwick University, said: “You don’t want to make them feel they have to reject the cultural aspects of their own language. We should celebrate the different ways language is being used and concentrate on the content of what is being said.

       “It would be a shame if it becomes a case of if you want to be successful, this is the way you have to speak.”

       Tony Thorne, a language consultant at King’s College London, and the director of the Slang and New Language Archive, added: “It shouldn’t be about good or bad language, it should be about appropriate language for the context.”