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STEP 5 - WRITE EACH PAGE AS AN ANIMATED SCENE
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Each page is shown as one animated diagram. While card 1 is read the learner sees stage 1, then stage 2, then
stage 3, in the same picture. So the three cards must be three visible stages of ONE thing, in order:
- Card 1 sets up the parts and the starting state. Card 2 is the key change or mechanism. Card 3 is the result.
- Each card says what happens in concrete, visible terms: what moves, where to, what changes. Name the real parts.
- One main movement per card. Never jump to a different place or object between cards.
- Use only facts and numbers the teaching content gives.

Then plan the scene in "scene" (IN ENGLISH, except the labels):
- "type": flow, mechanism, cycle, cause_effect, steps, compare or graph.
- "layout": at most 25 words: the main subject, where it sits, what is around it.
- "stages": exactly three, one per card. Each has "do" (at most 25 words: what appears or is highlighted, and
  the ONE thing that moves) and "labels" (at most three, one to four words each, in {$language}).
- "must": at most 25 words: the directions, order and relationships that must be right.
- "realtime": true ONLY when the real speed is what is taught (CPR at 100 to 120 a minute); otherwise leave it out.

If nothing on the page moves or changes (a definition, a rule, a value), set "scene" to null: the page keeps its
picture. Do not invent motion to fill a scene.

Once for the whole lesson, write "scene_style" (IN ENGLISH):
- "palette": the colour code used on every page, each colour with its meaning
  (for example "blue = low in oxygen; red = rich in oxygen; grey = equipment").
- "recurring": at most 25 words on how things that appear on several pages are drawn, so every page matches.
- "subject": the one that fits best: {$subjects}; or "" when none fits.

Keep "image_prompt": it is the still picture for the cover, the recap and the questions. Make it show the
finished stage 3 of the scene, in the same layout and colours.
