2.2 Language Demands of Subject Content and Tasks (Text Types & Genres)

Two Layers of Language Demand: Word Level and Sentence Level

Every piece of subject content and every task built around it makes language demands at two levels. Word-level demands are the vocabulary items a topic requires: technical terms (evaporation, isosceles, photosynthesis), general academic words that appear across subjects (analyse, compare, classify), and collocations specific to a field (carry out an experiment, draw a conclusion). Sentence-level demands are the grammatical structures a task needs in order to express subject content accurately: the passive voice for describing a process without naming an agent ('the water is heated', 'the mixture is filtered'), sequencing connectors for procedures (first, next, after that, finally), causal connectors for explanations (because, as a result, this causes), and comparatives or superlatives for reports that compare characteristics (larger than, the most common).

A CLIL teacher plans for both layers before the lesson, not during it. If a task asks learners to write a paragraph explaining why ice floats, the word-level demand includes density and the sentence-level demand includes a because / as a result structure to link cause and effect. If the teacher has not planned for the sentence-level demand, learners may know the content answer but lack the sentence pattern to write it, and the task will look like a language failure when it is really a planning gap.

Oral language carries its own version of the same two layers: a class discussion about an experiment's results needs the spoken vocabulary for describing data and the spoken sentence patterns for hedging and reporting findings, such as 'the results suggest that' or 'it seems that'.

Text Types (Genres) Used in CLIL

Subject content is communicated through recognisable text types, or genres, each with its own layout, organisation and purpose. TKT: CLIL groups the genres a CLIL teacher plans for as follows.

Beyond these six families, a CLIL teacher may also plan for other text types such as the letter, the narrative, and the email, each carrying its own conventions of layout and register.

Recognising the genre before planning a task matters because the genre decides both the organisation learners need to produce and the grammar that makes that organisation work. A cause-and-effect explanation and a one-sided argument essay might share the same topic and even some of the same vocabulary, but they demand different connecting language and a different overall shape.

Worked Example: One Topic, Different Genres, Different Language Demands

Take the topic of volcanoes taught in a CLIL geography class. The same subject content produces very different language demands depending on which text type the task uses.

• Explanation (process): 'Describe how a volcano erupts.' This needs sequencing and cause-and-effect language: first, magma rises; as pressure builds, this causes an eruption. The organisation is chronological and impersonal.
• Persuasion (advertisement or notice): 'Write a tourist notice warning visitors near an active volcano.' This needs imperative and evaluative language: do not approach the crater; this is an extremely dangerous area. The organisation is direct-address and instruction-like, not sequential.
• Recount (diary): 'Write a diary entry as a villager living near a volcano during an eruption.' This needs first-person, past-tense narration and personal, emotive vocabulary: I felt the ground shake; we ran to safety. The organisation follows the order events happened to the writer.
• Report: 'Describe the characteristics of an active volcano.' This needs factual, present-tense classifying language: an active volcano has a magma chamber; it typically erupts every few decades. The organisation opens with a general statement and lists features, rather than following a sequence or a personal timeline.

Four tasks, one topic, four different sets of grammar and vocabulary to plan for. A teacher who only plans the content (what a volcano is and how it forms) without planning which genre the task will use risks leaving learners without the specific language that the chosen text type requires -- a learner who can explain the eruption process may still struggle to write a persuasive safety notice or a factual report unless that genre's language has been taught separately. Planning which genre a task will use is therefore a language-demand decision as much as a content decision: it decides which grammar and vocabulary the lesson must teach before learners can attempt the task at all.