Response to investigate
The balloon gets bigger because the particles get bigger.
Practical disciplinary literacy
Science: disciplinary literacy in practice
Read the diagram, distinguish an observation from a model and explain a mechanism.
The task students are answering
Material to use
Display this situation: a sealed flexible container holds gas. It is warmed while external pressure stays constant. Its volume increases. Assume no gas escapes. Ask learners to sketch particles before and after; keep their number and size unchanged in the model.
Ask students
Why does the gas container expand when it is warmed? Explain using the particle model, rather than saying only that it gets hotter.
Expected response
A labelled before-and-after particle sketch and a short explanation connecting heating, particle motion and volume. State the constant-pressure condition.
What to look for
- Distinguishes the observed volume change from the model explanation.
- Shows particles moving faster on average, without growing or multiplying.
- Connects the expansion to the pressure condition.
How a response can develop
The model and sample responses below address the question above. Reveal the teaching interpretation after discussing what is clearer in the improved response.
Observe
The flexible container becomes larger when warmed.
Model
Gas particles move faster on average; the particles themselves do not grow.
Explain
The volume increases until internal and external pressures balance at the higher temperature.
More precise response
The gas volume increases as its temperature rises at constant external pressure. The particles move faster on average; their size does not increase.
Reveal the teaching interpretation
The first response exposes a model misconception. Establish the particle model with a sketch before working on a causal sentence. A fluent sentence can still be scientifically wrong.
These are invented teaching samples. One response alone does not establish proficiency, attainment or a learning difficulty.
Teacher preparation and teaching sequence
Prepare the material described in Visual model. Read the exact student question aloud and show the expected response before modelling. For Music and PE, supply the recording or demonstration first.
- Read or observe: introduce the task: Explain why a sealed flexible gas container expands when warmed at constant external pressure.
- Model: think aloud through the three-part model, connecting each decision to the evidence.
- Notice: compare the two sample responses. Identify one meaning difference, not just a difference in length.
- Rehearse: Ask learners to annotate what changes and what stays the same, then write a causal explanation.
- Transfer: Explain what happens when the same container cools. Label the model and state one condition.
Useful language to notice
The gas volume increases as its temperature rises at constant external pressure. The particles move faster on average; their size does not increase.
Highlight words that connect evidence, explanation and qualification. Choose a small useful phrase set rather than asking learners to memorise the entire model.
Use the task with your class
Student instructions
Why does the gas container expand when it is warmed? Explain using the particle model, rather than saying only that it gets hotter.
Produce: A labelled before-and-after particle sketch and a short explanation connecting heating, particle motion and volume. State the constant-pressure condition.
Independent follow-up
A sealed flexible gas container is cooled at constant external pressure. Predict the change in volume and explain it with a labelled sketch.
Use the fresh task after practice. Record what the learner achieves and which supports remain necessary.
Adapt and keep your resource
Edit these fields for your class or department. Drafts stay in this browser; use anonymised evidence. Download an editable text copy to keep it elsewhere.
Model the decisions, then invite a response
“Which change is observed, and which part of your explanation comes from the model?”
“What evidence supports that connection?”
“Which condition, exception or limitation matters here?”
Respond to the sample
The first response exposes a model misconception. Establish the particle model with a sketch before working on a causal sentence. A fluent sentence can still be scientifically wrong.
First establish the learner’s subject meaning through talk, a sketch or a familiar-language response. Then address one English choice that helps communicate that meaning.
Access, independence and department use
Access: introduce essential terms with a representation; allow bilingual notes, partner rehearsal and a brief sentence frame. Keep the subject reasoning.
Independence: use fresh content and remove the full model. Retain required access arrangements and record any prompts.
Department pilot: use this routine in one unit. Collect a small anonymised sample before and after teaching, note the support provided and review with an EAL colleague.
Plan a manageable pilotScience: disciplinary literacy in practice
Everyday communication and academic language
BICS is a useful shorthand for interpersonal communication; CALP draws attention to the language demands of academic learning. They are not two learner categories or a direct WIDA/CEFR conversion. Familiar conversation can conceal difficulty with a dense text or an unfamiliar subject explanation. Look at the task, context, support and individual language domains.
Plan from what learners can do
WIDA’s Key Uses provide a useful way to identify the communicative purpose: recount, explain, argue or discuss. Use the grade-band descriptors with the learner’s domain-specific evidence and choose support that keeps the subject thinking intact.
- Recount: Describe the stages of an investigation using an illustrated method.
- Explain: Explain how temperature affects particle motion using a diagram and observations.
- Argue: Decide which conclusion is best supported by an illustrative results table; justify and qualify the claim.
- Discuss: Compare two explanations of an observation and ask what evidence would distinguish them.
Open the subject language planner
Original teaching examples informed by WIDA Can Do Descriptors. They are not official descriptors or predicted assessment outcomes.