Domain: Healthcare — Nutrition & Dietetics
Target concept: Vitamin E, as an antioxidant, inhibits lipid oxidation, thereby delaying the darkening of color and the development of turbidity.

Video generation prompt: Take two identical beakers, each containing 10 mL of vegetable oil. Add 1 mL of vitamin E solution to one beaker and not add it to the other. Stir continuously while heating both beakers to approximately 180°C (near the oil's smoke point) for 30 minutes, then remove.

Evaluation guide:
(i) Target concept: Antioxidant-mediated inhibition of thermal lipid oxidation in edible oils.
Minimum mechanism: Oxidation of unsaturated fatty acids in vegetable oil under strong, sustained heat produces conjugated dienes and carbonyl compounds that absorb visible light (causing yellow→brown shift) and scatter light (causing turbidity); vitamin E donates hydrogen atoms to lipid peroxyl radicals, terminating chain propagation and preserving the treated oil's native optical properties. Heating to near the oil's smoke point for an extended period is used here to make the oxidative color/turbidity change visible within a short demonstration; this is an accelerated condition relative to normal oil storage.
(ii)Storyline: Frame 1–2: Two identical beakers side-by-side, each filled with pale yellow translucent vegetable oil. Frame 3–4: Dropper delivers amber-tinted vitamin E solution into left beaker only; no delivery to right. Frame 5–8: Identical stirring rods rotate continuously in both beakers while hot plates glow uniformly beneath both as the oil heats toward its smoke point. Frame 9–10: Final still: left beaker retains pale yellow clarity; right beaker shows visibly darker color and reduced transparency; contrast is stable, unoccluded, and centered in fixed viewpoint.

Manual:
Experimental Procedure
Take two identical beakers, each with 10 mL vegetable oil. Add 1 mL vitamin E solution to left beaker only. Stir both continuously while heating to approximately 180°C (near the oil's smoke point) for 30 minutes. Stop.
Observation of Experimental Phenomena
After heating, the untreated beaker shows darker color and increased turbidity; the vitamin E-treated beaker remains lighter and clearer.
Summary of Experimental Principles
Vitamin E, as an antioxidant, inhibits lipid oxidation in vegetable oil, delaying color darkening and turbidity development. Heating near the oil's smoke point for 30 minutes is used to accelerate this oxidation so the contrast becomes visible within a short demonstration; the underlying antioxidant mechanism is the same as at lower, real-world storage temperatures, just faster.

Prompt Grounding rubric:
level_1: No two beakers are shown; neither beaker contains a visible oil-like liquid; there is no visible addition of a vitamin E solution to either beaker; no heating or stirring action is shown; the two beakers are never shown together in the same shot for comparison.
level_2: Two beakers appear and hold some liquid, but at least one holds a liquid that does not look like vegetable oil (e.g., clear like water, or unidentifiable); no vitamin E solution is dispensed into either beaker; heating and/or stirring is missing, or is applied to only one beaker instead of both; the two beakers are not placed together for direct comparison.
level_3: Two beakers holding a pale-yellow, translucent oil-like liquid are shown together; a vitamin E solution is visibly dispensed (e.g., via dropper) into exactly one of the two beakers and not the other; both beakers are shown being heated and stirred at the same time as each other.
level_4: Building on the 3-point description, the vitamin E addition is visually unambiguous (a distinct-colored solution enters only one beaker via a single dispensing action), the stirring motion in both beakers looks continuous and equally vigorous, and a heat source (e.g., a hot plate) is visibly active under both beakers at the same time.
level_5: Beyond the 4-point description, the vitamin E solution is added once, before heating and stirring begin, and only to its designated beaker; no unrelated objects (labels, timers, extra containers) clutter the shot; the two beakers stay in the same place and orientation for the whole sequence, and the camera's view of both beakers side by side is never blocked or cut away.

Scientific and Causal Correctness rubric:
level_1: The two beakers look the same at the end of heating (no color or clarity difference between them), or the vitamin E-treated beaker ends up darker and more turbid than the untreated one, reversing the expected antioxidant effect.
level_2: A difference in color or clarity appears, but it does not track the antioxidant principle: the treated (vitamin E) beaker darkens or turns cloudy more than the untreated one, a color difference appears before the vitamin E is even added, or no difference is visible until after the heating has already stopped.
level_3: By the end of heating, the untreated beaker's oil looks visibly darker in color and less clear (more turbid) than the vitamin E-treated beaker's oil, even though both beakers were heated and stirred for the same length of time; no other change (bubbling, boiling over) dominates the shot enough to obscure this contrast.
level_4: Building on the 3-point description, the color/turbidity difference is confined to the oil itself, not just a stain on the glass or a ring at the liquid surface; the untreated beaker's oil darkens gradually over the course of heating rather than changing suddenly; the treated beaker's oil keeps a pale-yellow, clear appearance essentially unchanged from the start of heating.
level_5: Beyond the 4-point description, the color and clarity contrast between the two beakers is unmistakable and holds steady through the final frames without fading back or fluctuating; nothing in the shot (glare, reflection, shadow) could be mistaken for the darkening; and the only plausible explanation for the difference, given the shared heating conditions, is the presence or absence of the vitamin E solution.

Spatiotemporal Consistency rubric:
level_1: One of the beakers disappears from its spot and then reappears, or jumps to a different position, between frames; the oil level in a beaker changes suddenly with no stirring or spilling to explain it; the stirring rod starts or stops moving instantly with no slow-down or speed-up; the lighting in the shot changes drastically from one frame to the next for no visible reason.
level_2: One clear break occurs: the stirring rod vanishes for a frame and then reappears, the hot plate's glow turns on and off inconsistently, a shadow points in a new direction even though nothing suggests the light moved, or the background behind the beakers warps or shifts.
level_3: The two beakers stay side by side in the same spot for the whole sequence; the stirring motion in each beaker looks continuous and physically reasonable, without sudden jerks or impossible spins; the oil's surface moves in a way that matches the stirring rather than jumping to a new level; the lighting on the beakers looks the same in direction and brightness from the first frame to the last.
level_4: Building on the 3-point description, neither beaker appears to slide or float relative to the table or background behind it; there are no sudden jumps in the action (no frozen pauses, no skipped stages of stirring or heating); the stirring rod stays properly immersed in the oil rather than passing through the beaker wall; the heat source stays visibly on and correctly positioned under both beakers throughout.
level_5: Beyond the 4-point description, the stirring and any liquid motion speed up and slow down naturally rather than moving at a constant mechanical rate; no beaker, rod, or liquid surface stretches, pinches, or bends out of its normal shape in any frame; the depth relationship between the two beakers and the background stays consistent; and the stirring rod never appears to pass through the bottom or sides of a beaker or through the oil's surface in an unnatural way.