Domain: Natural Science — Chemistry
Target concept: Metals react with acids to produce bubbles (e.g., zinc in vinegar).

Video generation prompt: Two transparent beakers containing vinegar are placed side by side; a zinc strip is placed in the left beaker, and a copper strip is placed in the right beaker, then left undisturbed.

Evaluation guide:
(i) Target concept: Differential reactivity of metals with weak acid, manifested as presence/absence of gas evolution (bubbling) at metal surface.
Minimum mechanism: Zinc must be above hydrogen in reactivity series to displace H⁺ from CH₃COOH; copper must be below hydrogen to show no reaction; vinegar must be dilute aqueous acetic acid (not oxidizing agent); no catalysis, heating, or impurity-driven side reactions permitted.
(ii)Storyline: [Frame 0–2] Two empty transparent beakers placed side-by-side → [Frame 3–4] Vinegar poured into both (liquid fills beakers uniformly) → [Frame 5–6] Zinc strip lowered into left beaker until fully submerged → [Frame 7–8] Copper strip lowered into right beaker until fully submerged → [Frame 9–10] Both beakers held static; bubbles emerge exclusively on zinc surface and rise upward; copper surface remains inert and bubble-free. Viewpoint is fixed frontal medium shot; both beakers fully in frame at all times; no occlusion; lighting is even and top-frontal to ensure visibility of bubbles and metal surfaces.

Manual:
Experimental Procedure
1. Place two identical transparent beakers side-by-side on a flat surface.
2. Fill both beakers with equal volumes of clear vinegar.
3. Place a zinc strip fully inside the left beaker.
4. Place a copper strip fully inside the right beaker.
5. Leave both beakers undisturbed for observation.
Observation of Experimental Phenomena
Bubbles form continuously on the zinc strip surface in the left beaker; no bubbles form on the copper strip in the right beaker; vinegar remains colorless and transparent in both; no color change or dissolution observed in either metal.
Summary of Experimental Principles
Zinc reacts with acetic acid in vinegar to produce hydrogen gas (bubbles); copper does not react with vinegar under standard conditions due to its lower reactivity — demonstrating the metal reactivity series.

Prompt Grounding rubric:
level_1: Neither beaker shows both metal strips correctly placed: e.g., only one beaker appears in frame, no vinegar is visible in either beaker, the zinc strip is missing from the left beaker, the copper strip is missing from the right beaker, both strips end up in the same beaker, the two beakers are not positioned next to each other, or the beakers are never shown sitting undisturbed after the strips go in.
level_2: Both beakers appear next to each other with vinegar visible in each, but at least one of the following is wrong: the zinc strip is missing from the left beaker, the copper strip is missing from the right beaker, a strip is placed in the wrong beaker (e.g., zinc ends up in the right beaker), the two beakers are never shown together in the same shot, or the strips are still moving during what should be the still-observation phase.
level_3: The two beakers sit next to each other, each holding visible vinegar; the zinc strip is fully inside the left beaker and the copper strip is fully inside the right beaker; both strips stay motionless for the whole clip; every object stays visible and correctly placed, with no object disappearing, swapping places, or being blocked from view, but one or more minor visual mismatches remain, such as a beaker shaped unlike a typical lab beaker, a strip resting at an unusual angle, or noticeably uneven lighting between the two sides.
level_4: Everything required for score 3 holds, plus: the two beakers match each other in shape and proportions; both strips look properly metallic (grayish for the zinc strip, reddish-brown for the copper strip); the vinegar level looks the same in both beakers; there are no rendering glitches such as clipped edges, warped glass, or see-through gaps in either strip; the layout of both beakers and strips stays clear and unchanged throughout; only very minor flaws are allowed, such as a slightly mismatched reflection or a soft-edged shadow.
level_5: Everything required for score 4 holds, plus: the zinc strip shows a dull, matte gray surface with no oxidation sheen; the copper strip shows a uniform reddish-brown surface with no green patina; the vinegar in both beakers looks completely clear and colorless; the two beakers match each other exactly in shape, size, and glass thickness; both strips sit flat on the beaker floor or stand upright without bending; the camera holds a steady, centered, front-facing view of both beakers for the entire clip with no shakiness or flicker at the edges of any object.

Scientific and Causal Correctness rubric:
level_1: No observable phenomenon related to metal-acid reaction; or bubbles appear in both beakers; or bubbles appear only in right beaker (copper); or bubbles appear before strip placement; or bubbles persist after removal (but no removal occurs); or liquid changes color in either beaker.
level_2: Bubbles appear in at least one beaker, but causal assignment is inverted or ambiguous: e.g., bubbles appear only in right beaker (copper), or appear simultaneously in both beakers with identical intensity, or bubble onset occurs before strip contact, or bubbles are attached to container walls instead of metal surface.
level_3: Bubbles appear exclusively on the surface of the zinc strip in the left beaker, and no bubbles appear on the copper strip in the right beaker; bubbles are visibly attached to zinc surface and rise upward; no color change, dissolution, or corrosion visible in either strip; liquid remains colorless and transparent in both beakers; all phenomena visually distinguishable and align with expected reactivity difference.
level_4: Everything required for score 3 holds, and additionally: bubble formation begins only after the zinc strip is fully immersed and in contact with the vinegar; bubble size and frequency increase gradually rather than appearing all at once; the copper strip shows zero surface activity (no bubbling, no effervescence, no fizzing); there is no swirling or current in the liquid that could be mistaken for a reaction.
level_5: Everything required for score 4 holds, and additionally: every bubble visibly originates at the zinc strip's surface rather than from the beaker's bottom or sides; the stream of bubbles rises continuously and steadily upward; the copper strip shows no bubbling, shimmer, or disturbance of the vinegar around it; the first bubble on the zinc strip appears only after the strip has been fully and stably in contact with the vinegar, never before.

Spatiotemporal Consistency rubric:
level_1: The zinc strip, the copper strip, or one of the two beakers vanishes from view and reappears elsewhere in the clip; the camera suddenly pans, zooms, or rotates instead of holding the fixed frontal shot; the scene lighting flashes, fades, or shifts color abruptly; a beaker's glass wall warps or dissolves away; or a strip's shape fractures, splits, or bends in a way solid metal cannot.
level_2: One or more clear breaks remain: the zinc or copper strip appears to jump straight from the hand into its beaker with no visible lowering motion; the left or right beaker's position on the table shifts noticeably between two frames; the vinegar surface in either beaker jumps up or down without a smooth transition; the dark patch under the left beaker (holding the zinc strip) appears on a different side than the shot's light source would produce, with nothing in the scene to explain the change; or the footage stutters or skips during the strip-lowering action.
level_3: The two beakers stay side by side in the same relative position for the whole clip; the zinc strip stays fully inside the left beaker and the copper strip stays fully inside the right beaker without drifting, floating up, or sinking through the glass; the vinegar surface in each beaker stays level and undistorted; the shadows cast by the two beakers and strips keep the same direction and softness throughout; no beaker or strip visually overlaps or passes through another object; a brief, barely noticeable flicker at a shadow's edge is acceptable, but no beaker, strip, or liquid surface ever jumps position or disappears.
level_4: Everything required for score 3 holds, and additionally: neither strip nor beaker shows motion blur, even though both are meant to sit still after placement; the left and right beakers and the two strips stay visibly aligned in the same spot from one moment to the next with no perceptible sideways creep; the copper strip is never rendered as if floating behind the vinegar's surface when it should be fully submerged; no bubble appears rising from the zinc strip before the strip has fully touched the vinegar.
level_5: Everything required for score 4 holds, and additionally: the beaker rims, strip edges, and vinegar meniscus stay sharp and consistent in shape throughout the clip with no ghosting or color fringing at their edges; the curve of the vinegar surface where it meets each beaker wall looks physically natural and unchanging; the zinc strip's bubbling and the copper strip's stillness stay perfectly in step with the rest of the shot; nothing about the background or the two beakers looks delayed or out of sync with the rest of the scene.