The bookshelves at the Association for Science Education's annual conference were what really gave it away for Michaela Johnson.
The biology teacher, who is an examiner and textbook author, said that 10 years ago these displays groaned under a variety of GCSE and A-level textbooks, covering topics ranging from the biology of the food industry to enzymes in medicine.
These were books designed to promote a deeper understanding of the subject as students read widely. Today, though, she said, one type of educational resource predominates: the exam-board tie-in.
These are books endorsed by one of England's big three boards - AQA, OCR, and Edexcel - usually written by leading examiners, and which promise to help teachers gear their teaching to the requirements of the exam. They have become hugely successful in recent years in all major subjects.
For critics such as Ms Johnson and the Society of Authors, this is damning proof of how England's education system is becoming dominated by exams, at the expense of wider teaching.
They argue that the rise and rise of syllabus-specific textbooks shows how, from the age of 14, teaching amounts to nothing more than test preparation.
Are they right?
Anyone in doubt about the preponderance of exam board tie-ins should consider the blurbs with which the biggest publishers are promoting their latest products.
For example, Heinemann's website proclaims of its English materials: "GCSE English for OCRI provides a complete match to OCR. Focuses on assessment objectives."
An advert for new science resources says: "Nelson Thornes' support materials will provide a total match to the content of AQA's new specifications and the new assessment arrangements."
The launch of a new maths GCSE from September has seen the major publishers scrambling to get new textbooks out in time, and here, again, exam board endorsements are the order of the day.
Edexcel's website offers the following: "Written by Edexcel for teachers delivering the Edexcel GCSE, so you can be sure of a complete match to the new... Edexcel specifications".
It goes on: "Produced by a team that understands the common pitfalls in answers to past exam questions, allowing you to target your teaching at specific areas."
Several teacher-authors have confirmed to The TES that textbooks linked to specific exams, written by examiners and ideally endorsed by a board, now dominate educational publishers' priorities. One said: "I have written, or contributed to, 18 educational books. All are designed to meet the requirements of specific syllabuses."
Teachers might be entitled to ask what's wrong with this? After all, from the age of 14, exams loom large on the horizon of all young people. Doing well is hugely important to their future.
What, some would argue, is wrong with focusing on the assessment objectives of particular exams? If these tests are well-designed, tailoring teaching to ensure pupils hit a set of learning goals must be a good thing.
The counter-argument is that exam-focused teaching is narrowing learning.
By following these textbooks, teenagers will gain enough understanding to pass a particular test, but little else.
Ms Johnson, who writes biology books, spoke of the pressure she had come under from her publisher to remove material that was not strictly exam-relevant.
She said that a textbook she wrote in the 1990s had featured examples of ideal storage conditions for 19 different fruits and vegetables. Her publisher had wanted to cut the number of fruits, because pupils would be tested only on the storage of apples and tomatoes. Eventually, the number of examples was cut to eight.
Ms Johnson said that, increasingly, publishers wanted textbooks to tell pupils the answers sought by examiners in as easily digestible a form as possible. Students were not encouraged to work out answers for themselves, but presented with solutions.
If senior examiners were the ones suggesting the areas to concentrate on, so much the better, it was felt.
The way this works is often subtle. Ms Johnson said that any material that is not strictly relevant to an exam syllabus is now categorised as "background", rather than being integral to the text. This sent a signal to students concentrating on exam preparation that it could safely be ignored.
"Everything that's in the main part of the textbook is deemed to be something that you will need for your exam," she said. "But education is more than the exam at the other end."
Another author parted company with a publisher over a disagreement about the design of a textbook to support the new maths GCSE. The author said:
"It just seemed to be encouraging the worst tendencies of maths teaching: rote learning, teaching to the syllabus, doing what is necessary and no more, with no depth and no breadth". He added: "I'm not against the emphasis on results, but you don't get the results by just teaching to a particular target; you have to embed a piece of knowledge in a much wider context."
The textbook has yet to be published, so The TES could not check his claims.
Authors are not the only ones concerned about this trend. Last month, Ofsted reported that exam-endorsed maths textbooks were an effective tool for revision and popular with teachers and pupils. However, it said that most did not encourage students to make mathematical connections beyond the specific module covered by the book, and did not promote deeper understanding of the subject. The report said: "Effective teachers compensated for this, but in less confident hands the subject was reduced to techniques for passing examinations."
There were echoes of these concerns in February's report of the Nuffield Inquiry into 14-19 education which found that pupils were being spoon-fed through GCSEs and A-levels to such an extent that they arrived at university expecting to be told the answers.
Many members of the Society of Author's Educational Writers' Group are not examiners. So some might say it has an axe to grind in protesting about syllabus-specific textbooks, in which examiners are often favoured over other authors. But the society rejects this charge, pointing out that it is going beyond narrow self-interest in raising this issue.
Teachers say that the influence of textbooks on what gets taught depends on the skills and knowledge of staff. Those lacking specialist knowledge will rely on them.
Given the pressure on teachers over results, it seems hard to blame them for searching for any way they can improve their pupils' chances. To a certain extent, you cannot blame publishers or exam boards for producing textbooks in response to market demand.
But if the result is that education becomes synonymous with lessons in exam technique, many will say that Ms Johnson and the Society of Authors are right to blow the whistle.
* firstname.lastname@example.org Michaela Johnson is a pseudonym STUCK TO THE SYLLABUS?
Textbooks geared to the needs of particular boards' exams dominate resources published to support the new two tier maths GCSE.
Most are also focused on helping pupils of specific abilities gain better grades. Major textbook publishers include the following:
* Edexcel, which is owned by Pearson, is promoting its own textbooks. They are offered at foundation and higher tier, geared to the needs of its exams and supported by CD-Rom resources. They are written by a team of senior examiners, promise "a unique insight into exam success" and are distributed by Pearson.
* Heinemann is selling resources for Edexcel and AQA maths, including textbooks, software, practice books and revision books. Its AQA textbooks boast "mixed exercises at the end of every chapter for continual exam practice".
* Nelson Thornes is selling a selection of students', teachers' and homework books, plus electronic resources, to support AQA's linear and modular exams. Its website highlights its exclusive agreement with the board, which means it is AQA's only "preferred partner" for new textbooks.
* Hodder Murray offers specific resources for Edexcel's linear course, OCR's linear and modular GCSEs, the Welsh Joint Education Council's exams and will do so for exams from CCEA, the Northern Irish board.
* Collins has resources for AQA and Edexcel. They boast that "colour coding makes it easy to determine the level of demand and exam grade of every question".