Animal and plant cells (KS3)

Learning goal. Students can name and locate the main parts of animal and plant cells and say what each does. They can use the parts only plant cells have (cell wall, permanent vacuole, chloroplasts) to reason about an unfamiliar cell, including why not every plant cell has chloroplasts.

Who uses it. Year 7–9 students, on their own or in pairs, after a first lesson or microscope practical on cells. About 15 minutes. The teacher uses the "Now explain it" prompt to start a pair discussion.

The learning move. A representation to reason with. Students explore a labelled model at their own pace and compare its two versions. Then they apply it to a new case (a cell with a cell wall and a permanent vacuole but no chloroplasts) with feedback that explains, and explain it to a partner.

How students reach it. One .html file, opened in a web browser on the student's device. There is no login and no account, and it needs no internet. Publishing it as a link is a stretch (card 17).

Must do.

• Put a label next to each part, with a line to it.
• Let the learner switch between the animal and plant cell.
• Give part buttons that show where the part is found and what it does.
• Highlight the chosen part with a thicker outline (the cytoplasm, which has no outline, gets a darker fill instead), a thicker line and a bold, underlined label, not colour alone.
• Put a "How to read this model" note before the drawing: flat, simplified, not to scale, colours only tell parts apart, one example per label, some parts left out.
• Ask one reasoning question with feedback that explains. The question must not say where the cell came from.
• Give the drawing a text alternative that updates when the cell changes.

Must never do.

• Animate anything, or add realism or 3D decoration.
• Use a numbered key away from the drawing.
• Say or imply that all plant cells have chloroplasts.
• Go beyond the KS3 set of parts without the teacher checking.
• Save anything, load anything from the internet, or call an AI.

Acceptance criteria.

1. Every label's line starts on the part it names and ends beside its label, in both cells.
2. The animal cell shows exactly 4 parts and the plant cell 7, each in the right cell.
3. Every fact matches the teacher's textbook or specification (a human check).
4. It works with the keyboard only, with visible focus, at 320 px, at 4.5:1 contrast.
5. Nothing moves by itself, and there are no network requests.

Test cases (written before building).

Non-goals. No bacteria, fungi or specialised cells beyond the reasoning question. No ribosomes or other organelles beyond the KS3 set. Not to scale. No microscope photographs. No score.

Reuse plan (checklist item 11). Next lesson, students label a blank paper copy of each cell from memory. Two weeks later, one mixed retrieval question as a starter.

Check of learning (checklist item 12). Exit question a week later, without the tool: "A cell has a cell wall but no chloroplasts. Is it a plant cell or an animal cell? Explain." The explanation matters more than the answer.

Copy this, fill in the five [YOUR CLASS: …] gaps with your partner, then give it to your AI tool with the .html file.

Learning goal. [YOUR CLASS: in one sentence, what should students be able to name, locate or explain? This could be a different labelled model from your own subject, e.g. a volcano, a castle or a musical instrument.]

Who uses it. [YOUR CLASS: year group, when in the lesson, and alone or in pairs]

The learning move. A representation to reason with: explore a labelled model at your own pace, compare versions, then apply it to a new case with feedback that explains.

How students reach it. One .html file, opened in a web browser. No login, no account, no internet needed.

Must do. Labels sit next to the parts, with lines. The learner controls the pace and nothing moves unless the idea is about change. Buttons for each part show what it does. The chosen part is highlighted by more than colour. A "How to read this model" note comes first. One reasoning question with feedback that explains. A text alternative for the drawing. Keyboard and phone width must work. [YOUR CLASS: the parts to label, and one fact about each]

Must never do. Decorative animation or realism; a numbered key away from the drawing; saving anything; loading anything from the internet; calling an AI.

Acceptance criteria.

1. Every label points at the part it names.
2. [YOUR CLASS: how will you check every fact? Which textbook or specification page?]
3. It works with the keyboard only, at 320 px, at 4.5:1 contrast.
4. Nothing moves by itself.
5. No network requests.

Test cases. Keep T2, T3, T5 and T8 above, with your part names. Rewrite T1, T4, T6, T7 and T9 for your model. [YOUR CLASS: your reasoning question, its right answer, and the misconception each wrong option catches]

• An automated browser test ran every test case above at 320 px wide, using the keyboard only. All passed.
• Every leader line was measured: each starts on the part it names and ends beside its label, in both cells.
• Accessibility: text contrast at least 4.5:1, a visible focus outline at every Tab stop, controls at least 24 × 24 px, no sideways scroll at 320 px, nothing moves, and no issues found by the axe-core accessibility checker. The drawing's name and description update when the cell or the chosen part changes.
• The page made no network requests and stored nothing.
• Not tested: real screen readers, Safari and Firefox, or real phones. Try it on a class device before you use it.

What went wrong in testing, and the fix

• Labels too small on a phone, found by looking at a 320 px screenshot. The labels showed at about 8 px. Fix: the drawing was redrawn with a narrower cell and bigger labels, and the label test was run again on the new drawing.
• The reasoning question gave the answer away. It began "A cell from a plant's root…". It now describes the cell's parts only, and the feedback says where such a cell could come from.

The teacher's build checklist (12 points)

1. "Add a third button, 'Root hair cell', drawn in the same style: a plant cell with a long root hair and no chloroplasts, labelled in the same way. Change nothing else, and list every new fact so I can check it."
2. "Replace the reasoning question with this one: [your question], with three options and a note on each wrong option. Change nothing else."
3. "Rewrite every 'What it does' line for Year 7, at most 15 words each, keeping the facts the same. Change nothing else."