Grappling with how to support students to meet the increased demands of the curriculum was beginning to feel like an insurmountable task, when suddenly, the solution became clear.

James was usually a confident student, bristling with energy - a joker, even - but when I sat next to him and asked him to read, he became quiet and subdued.

I asked him to read a short passage from a Sherlock Holmes story that we were studying. Picking at his cuffs nervously, he began to read.

A few questions posed to James revealed the truth. His stop-start reading and lack of fluency exposed large gaps in his knowledge. James simply didn’t have the words to access what he was reading.

I was left asking: how many times is James being left struggling in the dark owing to the academic language of school? How many students have the same challenges? And how can we help them?

Renowned cognitive scientist Daniel Willingham, a professor of psychology at the University of Virginia, has shown just how crucial word knowledge is to accessing the school curriculum: “Studies have measured readers’ tolerance of unfamiliar vocabulary, and have estimated that readers need to know about 98 per cent of the words for comfortable comprehension.”

And evidence from England has shown that, alongside socioeconomic status, vocabulary was one of the significant factors that proved relevant to children achieving an A* to C grade in mathematics, English language and English literature GCSEs.

With the increased reading comprehension demands in every subject at every key stage and phase, students, like James, are floundering. For example, in science, research from the Royal Society and the Education Endowment Foundation has shown that the biggest barrier for disadvantaged students is reading scientific texts. The academic vocabulary of science is too often inscrutable for students like James.

And words like “fraction” can completely change in meaning between a maths lesson, a science lesson and a history lesson.

If we don’t attend to closing the vocabulary gap early, then students like James will fulfil a dismal prophesy of struggle and failure in school.

So how do we explicitly teach vocabulary? How can we support students to access more challenging reading beyond their chronological age?

In simple terms, we know that school students need something like 50,000 words in their personal lexicon to flourish in secondary and beyond. A primary school-age child is typically learning at a rate of around 4,000 or 5,000 new words a year. How can we supercharge this vocabulary development?

One simple way is tackling the vocabulary gap head-on with explicit vocabulary instruction. The evidence-informed SEEC model (developed for my new book, Closing the Vocabulary Gap) can be helpful for primary and secondary school teachers alike in offering a systematic approach:

• Select. What words do we need to choose as the most important vocabulary for students like James?
• Explain. Carefully pronounce the new word, write the word, offer a student-friendly definition and multiple examples.
• Explore. This is the fun bit. Talk about the words, use image association, compare synonyms and antonyms, dig into the roots of the word, and much more.
• Consolidate. This is often a missing link. We need to consciously revisit tricky academic vocabulary. Students need to use the words again and again, fostering vital repeated exposures to them.

Beyond this, we know that, ultimately, the most reliable method to broaden and deepen the vocabulary of our students is to get them reading a significant amount (a good reader can read a million words a year or more).

Leaving such reading to chance is not an option. We need to structure wider reading within the curriculum so that “reading for pleasure” is aligned with improving reading ability. For students like James, “reciprocal reading” - small peer group-led guided reading sessions - can prove a successful approach, helping them to deploy reading strategies deliberately with their peers. Many schools are weaving reading throughout the school day in innovative ways, from form time in the morning to an extended school day, so that students get the vital guided reading practice they need.

James, along with most students in classrooms across England, needed a great deal of support to close the vocabulary gap so that he could navigate his way through the curriculum. For him, reading a Sherlock Holmes story fluently, or a science textbook with understanding, will prove the making or breaking of his time in school.

Alex Quigley is director of Huntington Research School in York. He is the author of Closing the Vocabulary Gap, published by Routledge in April 2018