Domain: Natural Science — Biochemistry & Molecular Biology
Target concept: Excised leaves from albino maize seedlings were decolored and treated with iodine solution, confirming that the leaves remained yellow-white in color without any blue color change, exhibiting a clear and distinctive appearance.

Video generation prompt: Immerse the albino maize seedling leaves briefly in hot water, then transfer them to ethanol for decolorization. Rinse the leaves with distilled water, spread them flat in a petri dish, and apply iodine solution dropwise onto the leaf surface using a pipette. Demonstrate the clear equipment and step-by-step procedure.

Evaluation guide:
(i) Target concept: Absence of starch in albino maize tissue prevents iodine-induced color development.
Minimum mechanism: Iodine must contact a starch-containing substrate to form polyiodide-amylose helical complexes yielding blue-black color; absence of starch → no complex → no color change; albino maize genotype eliminates chloroplast biogenesis, abolishing starch accumulation.
(ii)Storyline: [Frame 0–2] Albino maize leaf (yellow-white, intact, no green pigment) is held and dipped into hot water container: leaf fully submerged, no bubbling or browning. [Frame 3–4] Leaf is lifted and placed into ethanol container: ethanol surrounds leaf completely, leaf remains yellow-white with no green residue. [Frame 5] Leaf is removed, rinsed under distilled water stream: runoff is clear, leaf stays yellow-white. [Frame 6] Leaf is laid flat in petri dish: edges fully extended, no curling, surface matte and dry. [Frame 7–9] Iodine dropper approaches, dispenses single amber-brown droplet that contacts leaf center and spreads radially: entire contacted area remains yellow-white with no hue shift. All steps occur from fixed frontal lab-view perspective; leaf remains fully visible and centered throughout; lighting is uniform and shadow-consistent.

Manual:
Experimental Procedure
1. Briefly immerse albino maize leaf in hot water.
2. Transfer leaf to ethanol for decolorization.
3. Rinse leaf with distilled water.
4. Spread leaf flat in petri dish.
5. Apply iodine solution dropwise onto leaf surface.
Observation of Experimental Phenomena
Leaf remains uniformly yellow-white before and after iodine application; no blue-black color develops at any stage.
Summary of Experimental Principles
Albino maize lacks functional chloroplasts and starch synthesis machinery; therefore, no starch is present to form the blue-black amylose-iodine complex.

Prompt Grounding rubric:
level_1: No albino maize leaf is shown; none of the hot-water container, ethanol container, petri dish, or iodine dropper appear; the immersion-decolorization-rinse-spreading-staining sequence is entirely absent; unrelated objects appear instead, such as a green (non-albino) leaf, a beaker of colored liquid, or a pipette dispensing plain water.
level_2: At least one correct prop appears (the albino maize leaf or the petri dish), but two or more required items are missing: no hot-water container, no ethanol container, or no iodine dropper/solution; at least two of the five procedural steps are skipped or performed incorrectly, e.g., the leaf is dipped in room-temperature water instead of hot water, or iodine is applied before the ethanol decolorization step.
level_3: All five props are present (albino maize leaf, hot-water container, ethanol container, petri dish, and iodine solution with dropper), and the five steps (hot-water dip, ethanol transfer, distilled-water rinse, flat spreading in the petri dish, dropwise iodine application) occur in the correct order, but one step's completion is not clearly shown, e.g., the leaf's submersion in the hot water is only partial, the ethanol does not visibly surround the leaf, or the iodine droplet's contact with the leaf surface is not visible.
level_4: All five props are present and unambiguous, and each of the five steps shows a clearly completed action: the leaf fully submerged in the hot water, then fully surrounded by ethanol, then visibly rinsed under a stream of distilled water, then laid flat with its edges extended in the petri dish, then contacted by a visible amber-brown iodine droplet that spreads across part of the leaf surface; no extra props appear, and no step is skipped, repeated, or reordered.
level_5: Every 4-point condition holds, and in addition the leaf's position relative to each container stays continuous across cuts (it is never shown already inside a container without a visible entry), the petri dish and both liquid containers keep the same size, shape, and orientation whenever they reappear, the camera framing stays fixed for the whole five-step sequence with no zoom or pan that could hide an off-screen step, and the leaf's own scale and orientation carry over unchanged from one step to the next.

Scientific and Causal Correctness rubric:
level_1: The leaf appears green or otherwise pigmented at any point; the iodine step produces a blue-black stain anywhere on the leaf; the leaf is not yellow-white before or after the iodine application; the ethanol step shows no decolorizing effect at all (the leaf keeps its original color); or the hot-water step visibly damages the leaf (browning, curling, or disintegration) in a way the procedure does not call for.
level_2: The leaf is yellow-white before the iodine step, but the iodine produces any blue, purple, black, or otherwise dark localized stain wherever it contacts the leaf; OR the leaf is still green or brown after the ethanol step (no visible decolorization) even though it ends yellow-white after iodine; OR the hot-water immersion visibly browns or curls the leaf's edges, a change the five-step procedure does not call for and that no shown step explains.
level_3: The leaf is yellow-white both before and after the iodine step; the ethanol container shows the leaf immersed and pale yellow-white with no green remaining; the hot-water step leaves the leaf's color and shape unchanged; the distilled-water rinse produces clear, uncolored runoff; the iodine droplet contacts the leaf but the leaf's own tissue color does not shift toward blue-black anywhere; however, one causal step is ambiguous, e.g., the ethanol immersion is shown but the leaf is partly obscured so pigment removal is not confirmed, or the iodine droplet's contact point is hard to see.
level_4: The leaf is yellow-white before the hot-water step and stays yellow-white through both the hot-water and ethanol steps, with no green or brown hue appearing at any point; the ethanol visibly carries away any faint residual pigment if present; the distilled-water rinse yields clear runoff; after the iodine droplet spreads across the contacted area, the leaf tissue itself remains yellow-white (only the droplet's own amber-brown color is visible where it sits, with no blue-black or darker tint developing in the leaf beneath it), matching the expected result that albino maize tissue has no starch available to bind iodine.
level_5: Every 4-point condition holds, and in addition the leaf's yellow-white appearance is uniform in every frame, with no mottling, gradient, or localized darkening anywhere on the leaf, including under and around the iodine droplet; the iodine solution itself is visibly amber-brown before it touches the leaf and keeps that same amber-brown hue afterward without deepening or spreading a darker color into the leaf tissue; the ethanol is shown colorless and transparent with the leaf clearly visible inside it; and no incidental staining, shadow, or lighting change on the leaf could be mistaken for a color shift.

Spatiotemporal Consistency rubric:
level_1: The leaf jumps between containers with no visible transfer motion; a container (the hot-water bath, the ethanol bath, or the petri dish) vanishes or appears without being carried in by hand; the bench lighting jumps from bright to dim between two consecutive shots with no dimming visible; the leaf's orientation flips instantly with no rotation shown; the petri dish changes size or shape between shots; or the iodine droplet appears already resting on the leaf with no dropper or delivery motion shown.
level_2: At least two of the following occur: an abrupt cut skips over an action, e.g., the leaf is dry in one shot and already sitting in the ethanol in the next with no immersion shown; a container's position on the bench shifts by a large, unexplained amount between steps; the leaf's visible orientation changes inconsistently between shots, e.g., which end points toward the camera flips without a corresponding turning motion; a shadow on the bench appears, disappears, or switches sides abruptly; or the ethanol level in its container rises or falls between shots with no liquid poured or removed.
level_3: Exactly one minor spatiotemporal flaw occurs: either (a) a single cut skips part of an action, e.g., the leaf is shown just touching the hot water's surface, then in the very next shot already fully submerged, with the intervening motion missing; (b) a highlight or reflection on a container shifts position once with no corresponding camera or light move; or (c) the petri dish shifts slightly on the bench between shots while keeping its orientation and apparent size; otherwise the leaf and every container keep their shape and structure intact throughout.
level_4: No container or leaf ever appears or vanishes without a visible transfer motion; the leaf is never distorted or torn; the lighting stays even across the hot-water, ethanol, rinse, and iodine steps with no sudden flicker; every transition is either continuous motion (a hand moving the leaf) or a clean cut that does not hide an incomplete action; each container keeps the same position, size, and orientation whenever it reappears; the leaf's own motion (being lifted, carried, and laid down) looks physically natural rather than stiff or floating; and any shadow the leaf casts stays on the same side, consistent with a single, unmoving light source.
level_5: Every 4-point condition holds, and in addition the motion is continuous across the whole sequence: the leaf is visibly lifted from the hot water, carried through the air, and lowered into the ethanol; the ethanol's surface visibly settles once the leaf enters it; the rinse water is seen flowing over the leaf's surface; the leaf lies flat in the petri dish without an unexplained bounce or slide; and the iodine droplet forms at the dropper tip, falls, contacts the leaf, and spreads outward in one unbroken, physically plausible motion, with no part of this chain skipped or reversed.