Monosyllabic adolescents may be nothing new, but the latest research suggests a big chunk of them do not know enough words to do well at school.
According to academics, four out of 10 pupils in their first year of secondary school have such a limited vocabulary that it is affecting their learning.
Many teachers from the 800 secondaries involved in the Oxford University Press research say the problem is worsening.
They blame the "word gap" on too little reading for pleasure.
Studies suggest breadth of vocabulary is strongly influenced by the number of words a child comes into contact with on a daily basis.
This includes conversations with parents, siblings and friends, as well as what they read.
The report, focusing on schools in England, says the number of pupils with limited vocabulary remains "stubbornly high" across all age groups, despite a range of programmes addressing literacy.
And 80% of the teachers surveyed said children with limited vocabulary would find it "extremely challenging" to understand test papers.
A very high proportion of the teachers said the word gap held back progress in not just English (91%), but in history (90%), geography (86%) and religious studies (78%).
Lionel Bolton, of the Oxford University Press, said: "Whether a child is 11 years old and in Year 7, or 16 years old and in Year 11, if there are words in a task that they do not understand, they will struggle to complete the task.
"The 11-year-old is likely to be able to ask for help or access a dictionary; a 16 year old in their GCSE exam cannot.
"And if they do understand all the words in the task, if their vocabulary is lower than their age, their written response may be less articulate, less effective, and ultimately achieve a lower mark.
"This of course is not new - it has ever been thus.
"But with the changes that have been brought in by the new GCSE exams - increased rigour, removal of controlled assessment, and tiering in most subjects - the vocabulary challenges posed are even more pronounced."
Geoff Barton, general secretary of the Association of School and College Leaders - and an English teacher for 32 years - said: "In reality the word gap will depend on your circumstances rather than your choices - your home, your family, the richness of language and relations, the presence of books and conversations, the habits you form as you grow up.
"These are things largely beyond our control."