Domain: Natural Science — Chemistry
Target concept: Copper metal, when heated in air, forms a black copper oxide layer.

Video generation prompt: A bright copper strip was held by metal tongs and strongly heated in air, then removed and allowed to cool.

Evaluation guide:
(i) Target concept: Oxidation of elemental copper via thermal reaction with atmospheric oxygen to form copper(II) oxide.
Minimum mechanism: Copper must be in elemental metallic state (bright, conductive, reddish-orange) prior to heating; heating must supply activation energy for O₂ dissociation and surface reaction; oxide formation requires direct exposure to air (no sealed environment); product must be stoichiometric CuO (not Cu₂O) yielding dense black color, not red.
(ii)Storyline: Phase 1 (0–2s): Bright copper strip gripped at ends by metallic tongs, centered in frame, ambient lighting. Phase 2 (2–5s): Flame contacts mid-section: immediate localized brightening (incandescence), followed by progressive blackening spreading outward from contact zone. Phase 3 (5–6s): Tongs withdraw strip fully from flame; blackened region fully formed and stable. Phase 4 (6–10s): Strip held still in same orientation; black layer remains uniform, non-reflective, and unchanging: no gloss recovery, no edge fading, no thermal distortion. Perspective: Fixed frontal view, full-strip visibility maintained; no occlusion; lighting dominated by flame during heating, ambient-dominant during cooling.

Manual:
Experimental Procedure
1. Hold a bright copper strip with metal tongs.
2. Strongly heat the middle section of the strip in open air using a flame.
3. Remove the strip from the flame.
4. Hold it motionless in air to cool.
Observation of Experimental Phenomena
The bright reddish-orange copper strip turns uniformly black during heating; the black layer remains unchanged after removal and persists throughout cooling.
Summary of Experimental Principles
Copper metal reacts with oxygen in air when heated, forming black copper(II) oxide (CuO).

Prompt Grounding rubric:
level_1: No copper strip appears anywhere in frame; no metal tongs are shown; there is no flame or visible heat source; the cooling phase after removal is absent; the scene does not depict any part of holding, heating, or cooling a copper strip.
level_2: A copper strip or a pair of tongs appears, but not both; or the copper strip is present without any flame/heating element; or the sequence order is scrambled (e.g., the strip already appears black before any flame contact, or cooling is shown before heating); no coherent hold→heat→remove→cool demonstration is visible.
level_3: The copper strip, the metal tongs gripping it, and an open flame or glowing heat source are all present in frame; the strip is heated while held by the tongs, then visibly withdrawn from the flame, then held still to cool, but one of these four steps (hold, heat, withdraw, cool) is hard to distinguish, e.g., the withdrawal moment is ambiguous or the cooling period is too brief to separate from the heating shot.
level_4: The bright reddish-orange copper strip, the rigid metal tongs, and the flame contacting the strip's mid-section are all clearly and unambiguously shown; the four-step sequence (tongs grip strip → flame heats the strip → strip is pulled fully clear of the flame → strip is held motionless in open air) is visually distinct with no missing step, no extra objects (e.g., no second strip or second tool), and no substitution of tool or material.
level_5: Everything required for score 4 holds, AND the tongs keep the same grip point on the strip the entire time, the strip stays fully inside the frame and roughly centered through every phase, the flame only ever touches the strip itself (never the tongs), the camera framing never zooms, pans, or cuts to a different angle, and the cooling phase shows no second dip into the flame or any other object touching the strip.

Scientific and Causal Correctness rubric:
level_1: The copper strip shows no color change at any point, or is already black/gray/oxidized before heating starts, or turns an unrelated color such as green, blue, or white during or after heating.
level_2: The strip starts bright and either stays bright with no color change after heating, or turns to a non-black tone (e.g., brown, purple, or a patchy mix of colors), or the blackening appears before the flame touches it or only during the cooling phase, so heating and blackening are not causally linked.
level_3: The bright reddish-orange strip visibly darkens to black while in contact with the flame, the black color persists after the strip is pulled away and stays black through cooling with no reversal, the color change goes directly from bright metal to black without an intermediate red-brown stage, and the black region is roughly even across the heated area, though the blackening may be incomplete (e.g., only the tip darkens) or partly hidden by smoke or glare.
level_4: Everything required for score 3 holds, AND the black layer appears only where the flame actually touched the strip, the end still gripped by the tongs stays bright, the black surface looks matte and non-reflective with no flaking or powder falling off, and no other chemical event appears (no melting, bubbling, sparking, or visible vapor); heating leads to blackening which then persists through cooling.
level_5: Everything required for score 4 holds, AND the blackening starts as soon as the flame touches the strip, spreads outward without stalling while heated, stops advancing the instant the strip leaves the flame, and stays exactly as dark through the entire cooling period with no patch regaining shine; the final black matches the dull, opaque look of copper(II) oxide with no bluish, brownish, or greenish tint and no red patches that would suggest Cu2O instead of CuO.

Spatiotemporal Consistency rubric:
level_1: The strip jumps to a different position or disappears and reappears between shots; the tongs vanish and reappear; the flame skips around the frame with no continuous motion; the black layer appears or disappears with no visible cause; the shot cuts abruptly or the strip flips/rotates with no tongs motion to explain it.
level_2: At least one major break in continuity occurs: the strip's position changes with no visible motion connecting the two positions, the tongs lose and regain their grip with no visible re-gripping action, the black layer appears all at once instead of spreading, or the strip looks suddenly cooler (e.g., frost or condensation) with no heating shown beforehand; several visible cuts or heavy stutter are present.
level_3: The tongs move smoothly through gripping, lifting, and withdrawing the strip; the strip itself moves as one rigid piece without bending or warping; the heated zone grows gradually rather than jumping in size; the blackening spreads across the surface without skipping sections; the flame stays the visible light source with no unexplained shadow flips; and there is no flicker, ghosting, or stutter that breaks up the sequence of events.
level_4: Everything required for score 3 holds, AND the tongs and strip keep a consistent depth relationship with no parallax mismatch, the strip never flattens or stretches from a perspective error, no motion blur hides whether the strip is still bright or already black, the flame's brightness stays steady rather than spiking or dropping without cause, and the cooling phase shows no shimmer or heat-haze distortion that would only make sense right next to an active flame.
level_5: Everything required for score 4 holds, AND the tongs' withdrawal motion slows naturally rather than stopping abruptly, the tongs stay rigid with no rubbery flex or hinge wobble, the blackening advances at a steady visual pace across the heated zone, the strip and flame show no visible shake or frame-to-frame instability in their outlines, and the camera holds one fixed position and focus for the full clip with no viewpoint drift.