Domain: Healthcare — Nutrition & Dietetics
Target concept: Iodine solution reacts with starch in bread or potatoes.

Video generation prompt: Place the bread and raw potato slices on a white plate, side by side, and add a few drops of iodine solution to each surface.

Evaluation guide:
(i) Target concept: Iodine-starch reaction produces identical dark blue-black coloration on starch-rich foods.
Minimum mechanism: Both bread and raw potato must contain amylose; iodine solution must be aqueous potassium iodide-based; contact must be direct and surface-localized; color development must be near-instantaneous and chemically specific.
(ii)Storyline: [Frame 0–2] White plate enters view; bread slice and raw potato slice are placed side-by-side in fixed positions. [Frame 3–5] Iodine dropper enters frame from above, hovers, then dispenses drops onto bread surface; color change appears immediately at contact points. [Frame 6–8] Dropper repositions and dispenses drops onto potato surface; identical color change appears immediately at contact points. [Frame 9–10] Final static shot holds both items with fully developed, non-diffusing, high-contrast blue-black spots. Perspective: Fixed frontal overhead or 30° oblique angle; full visibility of both food surfaces and drop impact zones required at all times.

Manual:
Experimental Procedure
1. Place one slice of white bread and one raw potato slice side-by-side on a white plate.
2. Using a dropper, apply 2–3 drops of iodine solution onto the surface of the bread slice.
3. Using the same dropper, apply 2–3 drops of iodine solution onto the surface of the raw potato slice.
Observation of Experimental Phenomena
Both bread and raw potato surfaces turn dark blue-black or deep purple where iodine drops land — immediate, localized, and identical in hue and intensity.
Summary of Experimental Principles
Iodine solution forms a complex with amylose starch, producing a characteristic dark blue-black color; both bread and raw potato contain sufficient amylose to yield this reaction.

Prompt Grounding rubric:
level_1: No white plate, no bread slice, no raw potato slice, and no iodine dropper or bottle appear anywhere; nothing resembling the two foods being placed side by side or iodine being applied is shown.
level_2: The plate is visible along with either the bread or the potato slice, but not both; a dropper or bottle of iodine appears but never actually touches either food's surface; or the two food items appear stacked, overlapping, or never appear together in the same shot.
level_3: A white plate holds both a bread slice and a raw potato slice, and an iodine dropper or bottle is used to apply liquid to at least one of the two surfaces; both food items are visible together on the plate, positioned near each other even if not perfectly aligned.
level_4: Both the bread slice and the raw potato slice sit fully visible side by side on the white plate, in the same plane and under the same lighting; the iodine dropper visibly dispenses drops onto both surfaces, with the moment of contact clearly shown for each; nothing blocks the view of either food while the drops are applied.
level_5: All of score 4, plus the bread and potato slices are intact and clearly separated from each other with a visible gap between them; the iodine comes from a labeled dropper bottle with a visible tip; the drops fall as distinct round droplets that land on each food's surface in immediate succession; neither food item shifts position between the placement shot and the drop-application shot, and there is no camera cut or zoom in between.

Scientific and Causal Correctness rubric:
level_1: After the drops land, neither food surface shows any color change at all: the bread crumb stays its pale beige color and the potato flesh stays off-white, while the iodine sitting on each surface still shows its own native amber-brown liquid color, unreacted.
level_2: Only one of the two foods darkens where the drops land while the other shows no reaction at all; or both foods change to the same wrong color, such as turning greenish, reddish, or only slightly darker brown rather than blue-black; or a color change appears on a food's surface before the drop actually reaches it.
level_3: Both the bread and the potato darken somewhat where the iodine touches them, but the resulting shades differ noticeably between the two (for example, the bread turns a solid dark blue-black while the potato only turns a light gray-brown), so the reaction looks inconsistent between two foods that both contain starch.
level_4: Both the bread's and the potato's drop-contact spots turn a dark blue-black (or deep purple) color that matches between the two foods; the color change stays confined to where the drops actually touched; no other part of either food, and no part of the plate, shows any color change.
level_5: The bread's and the potato's drop-contact spots both show the same dark blue-black (or deep purple) color, appearing on both foods either at the same time or in quick succession matching when their drops were applied; the color stays confined to its original contact spot for as long as it remains visible, without spreading, fading, or bleeding outward into the surrounding food.

Spatiotemporal Consistency rubric:
level_1: The plate, bread, or potato appears to jump to a new position or vanish and reappear between shots; a color change appears on a food's surface before the dropper ever reaches it; the lighting or background changes abruptly between the bread-application moment and the potato-application moment, as if they were filmed in different places.
level_2: The dropper or a food item stretches, flattens, or otherwise distorts unnaturally while moving; the plate visibly rotates or slides on its own between shots; the bread and potato shift position independently with no visible cause; a hard cut interrupts the sequence between applying drops to one food and applying them to the other.
level_3: The plate, bread, and potato keep the same arrangement relative to each other throughout, with only minor handheld-style shake and no item disappearing or relocating; the dropper's descent toward each food looks physically plausible, moving downward under its own motion rather than floating; the whole sequence plays as one continuous shot with no visible cuts.
level_4: The plate, bread, and potato keep the same position, scale, and orientation for the entire sequence; the dropper's movement toward each food is smooth and direct, without stutter or jumpy motion; there is no visible misalignment, warping, or sudden perspective jump between frames; the plate's surface looks the same texture and brightness throughout.
level_5: The plate stays fixed in the frame while the bread and potato hold identical relative positions and angles from the first frame to the last; the dropper approaches each food along one continuous, natural path without deviating or jumping between them; each drop falls straight down as a coherent round droplet; no blur ever obscures the outline of the plate or either food, and the depth relationship between foreground and background never shifts.