LAUNCH · Edexcel GCSE Biology 1BI0 Foundation · Paper 1 · Topic 1 · Week 4
| Key word | What it means |
|---|---|
| describe | Say what happens. No reason needed. |
| explain | Say WHY it happens — 'because' usually belongs in the answer. |
| point | A relevant idea or reasoning step; credit depends on the question. |
| gradient | The difference in concentration that particles diffuse down. |
| adaptation | A feature that makes diffusion faster — surface area, distance, gradient. |
Session plan: 40-minute session: Arrival 3; overview 1; I Do 1 4; We Do 1 4; I Do 2 3; We Do 2 4; independent work 15; feedback and next step 3; exit 3. Title orientation is untimed. The optional two-minute evidence check sits inside independent time. Keep extra practice available; use the core question, a contrasting example and a recheck before extending.
Name: ____________________ Tier ringed by adult: ◆ Supported ▲ Standard ★ Stretch Date:
I can answer exam-style diffusion questions independently, matching my answer to the command word.
Match the command word to what it asks: describe / explain.
Write what an 'explain' answer must contain that a 'describe' answer does not.
A 3-mark 'explain why oxygen diffuses into the blood' — list the three points you would make.
'It spreads out.' (Explain diffusion, 3 marks) → ______________________________
'Oxygen goes in.' (Explain, 3 marks) → ______________________________
'The wall is thin.' (Explain fast diffusion, 2 marks) → ______________________________
A neat paragraph for a 1-mark 'name' → ______________________________
'Higher oxygen in alveolar air; random crossings both ways; more crosses air to blood than back.' → ______________________________
'Because.' with no science after it → ______________________________
Explain the initial net movement of oxygen from alveolar air into arriving blood. [3] — Alveolar air has a higher oxygen concentration than the arriving blood (1). Oxygen moves randomly and crosses in both directions (1). More crosses from air to blood than back initially, so the net movement is down the gradient (1). These are the criteria for this teacher-authored practice item.
Show-me lesson: repair a weak answer, then answer your own. 'Oxygen goes in.' is incomplete. Add the concentration comparison, random movement both ways and the net imbalance; check this item’s criteria. You mark your OWN answer against the board — is the concentration comparison there? random movement? the net result? Tick the points you made. Method, never a grade.
describe, explain, point, gradient, adaptation
Show-me lesson: repair a weak answer, then answer your own. 'Oxygen goes in.' is incomplete. Add the concentration comparison, random movement both ways and the net imbalance; check this item’s criteria. You mark your OWN answer against the board — is the concentration comparison there? random movement? the net result? Tick the points you made. Method, never a grade.
describe, explain, point, gradient, adaptation
Show-me lesson: repair a weak answer, then answer your own. 'Oxygen goes in.' is incomplete. Add the concentration comparison, random movement both ways and the net imbalance; check this item’s criteria. You mark your OWN answer against the board — is the concentration comparison there? random movement? the net result? Tick the points you made. Method, never a grade.
describe, explain, point, gradient, adaptation
Task: Four exam-style questions with the command word highlighted and sentence starters for each point.
Task: Six exam-style diffusion questions including one describe and one 3-mark explain, points numbered.
Task: Six questions including a 4-mark explain, then review two of your own answers and state which point would gain the missing mark.
Why must you check the particular question and its criteria?
Pearson Edexcel GCSE (9–1) Biology 1BI0 (Foundation, grades 1–5); GCSE Combined Science 1SC0 F where appropriate; AQA UAS science units
Records what was observed, and at which level of independence.
| Pupil | ____________________ |
| Lesson | Master: Explaining Diffusion in the Exam — LAUNCH Science · Week 4 |
| Date | ____________________ |
Observed in this lesson
☐ Distinguished describe from explain.
☐ Checked the response against the question-specific criteria.
☐ Linked concentration evidence to the net direction of diffusion.
Assessor comment
Ring the tier the pupil actually worked at
| ◆ Supported | ▲ Standard | ★ Stretch |
Assessor name ______________ Role ____________ Signature ______________ Date ________
Space: Exam-style work raises the temperature. This is practice — the Topic 1 assessment is separate and you will know when it happens.
Voice: Challenge any question that seems unfair. Sometimes the question is the problem.
Audience: Your improved answers go into the Topic 1 folder as the revision set.
Influence: The class chooses which question type gets one more worked example.
Closing the loop: this one ends on paper — your own hand, or your words scribed by an adult. Saying it aloud starts the loop; writing it is what closes it. Pass is always allowed.
What I said, and what it changed:
Keep with your portfolio.
| Pupil name: | Date: |
| WWW (What Went Well): | |
| EBI (Even Better If): | |
| Level worked at: Supported / Standard / Stretch | Evidence filed: Yes / Not yet |
| Pupil response — my next step: | |