Domain: Natural Science — Chemistry
Target concept: Copper metal reacts with oxygen

Video generation prompt: Place a small amount of solid copper metal in a crucible, heat the crucible directly with a flame outside any container until very hot, then lower it into a transparent flask filled with oxygen gas and hold it there.

Evaluation guide:
(i) Target concept: Thermal oxidation of elemental copper to copper(II) oxide when heated copper is exposed to concentrated oxygen gas.
Minimum mechanism: Copper begins to oxidize as soon as it is hot enough, even in ordinary air, so some initial darkening during the external heating phase is expected and correct; the hot, possibly already-darkened crucible and copper are then lowered into a flask pre-filled with oxygen gas (not air), where the surface oxidation continues and completes; the reaction proceeds via solid-gas surface oxidation without melting or open flaming; the product is stoichiometric CuO (black), not Cu₂O (red) or a hydrated compound.
(ii)Storyline: [Phase 1: Setup] Crucible centered in frame, empty → copper placed inside (visible as a discrete reddish-orange solid). [Phase 2: External heating] A flame is applied directly to the crucible and copper outside the flask until the copper is visibly hot/glowing; the surface may already begin to darken from oxidation in the surrounding air during this step. [Phase 3: Insertion] The heated crucible is lowered into the transparent oxygen-filled flask. [Phase 4: Transformation] Once inside the oxygen atmosphere, the copper surface continues to lose metallic luster and darkens further toward a uniform black/brown; no bubbling or liquid pooling. [Phase 5: Completion] The crucible is withdrawn or heating ends; the final residue is a matte black/brown solid occupying the original copper's location; the flask remains structurally intact throughout. Perspective: Fixed frontal macro view focused on the crucible and flask mouth; all phases fully visible without occlusion or cutaways.

Manual:
Experimental Procedure
1. Place a small amount of solid copper metal into a ceramic crucible.
2. Hold the crucible in a flame outside the flask and heat until the copper is visibly very hot.
3. Lower the heated crucible into a transparent flask filled with oxygen gas and hold it there, without further direct flame contact.
Observation of Experimental Phenomena
As the copper is heated in the flame, its surface may already begin to darken from reacting with oxygen in the surrounding air; once lowered into the oxygen-filled flask, the darkening continues and completes, turning the copper into a uniform black or dark brown non-metallic solid; no flame, spark, or gas evolution is observed; the product remains solid and contained within the crucible.
Summary of Experimental Principles
Copper metal oxidizes once it is hot enough, whether the surrounding gas is ordinary air or pure oxygen; heating it directly in a flame can already start the reaction, and lowering the hot copper into the concentrated-oxygen atmosphere of the flask drives the oxidation to completion, forming copper(II) oxide (CuO), a black ionic compound: 2Cu(s) + O₂(g) → 2CuO(s).

Prompt Grounding rubric:
level_1: None of the required elements appear: no crucible, no solid copper, no oxygen-filled flask, and no heating action of any kind, or the scene shows something unrelated entirely.
level_2: Only one of the three objects (crucible, copper, or oxygen flask) is clearly shown, and no heating or insertion action occurs; or copper is never placed into the crucible at all.
level_3: The crucible, the solid copper inside it, and a transparent flask containing oxygen (visually distinguishable from an ordinary empty jar through gas-collection setup context) are all present; the crucible is heated by an external flame and then lowered into the flask, but the two-phase order is jumbled (e.g., the crucible appears inside the flask before any heating is shown) or one action is only partially depicted.
level_4: The copper is visibly placed into the crucible before any heating begins; the crucible and copper are heated directly by an external flame outside the flask until the copper is visibly hot; the heated crucible is then lowered into the oxygen-filled flask; the flask remains clearly identifiable as the oxygen-containing vessel throughout, and no unrelated objects dominate or block the crucible/flask view.
level_5: All of the above holds, and every transition is shown with clear physical continuity: the copper keeps its size and shape as a solid piece from placement through heating (any solid form [chunk, foil, granules, or powder] is acceptable, so long as it is not liquid), with its initial metallic luster visible before heating; the flask is transparent and stays intact and stationary once the crucible is inside; the viewpoint stays fixed on the crucible/flask system with no object entering or leaving frame unexpectedly.

Scientific and Causal Correctness rubric:
level_1: The copper shows no color change at any point in the video, neither during the external heating nor after insertion into the oxygen flask; or it turns a color inconsistent with CuO formation (green patina, blue, or brick-red Cu₂O).
level_2: The copper changes color, but to an incorrect hue (green, blue, or red rather than black/brown); or the color change has no plausible connection to heating (e.g., it darkens while cold, or before the flame ever touches it); or the copper is already fully black before any heating is shown.
level_3: The copper visibly darkens toward black/brown as it is heated in the flame, and the darkening is present or continues to progress once the crucible is inside the oxygen-filled flask; the product stays confined to the crucible; there is no explosion, spattering, or open flaming; the residue is a solid, not smoke or liquid.
level_4: All of the above holds, and the color change is one-directional (reddish-orange toward black/brown, with no reversal or flickering back); once inside the flask, the darkening visibly progresses further or completes rather than remaining static, showing that the oxygen atmosphere continues the reaction; no visible glowing, sparking, or open flame is seen on the copper itself while inside the flask.
level_5: All of the above holds, and by the end the copper's surface is matte and fully black/brown with no visible reddish-orange remaining and no metallic sheen; the flask's interior stays visually clear (no smoke, fogging, or condensation); the sequence reads clearly: copper is heated and begins darkening → is lowered into the oxygen flask still incompletely reacted → the darkening completes while inside the oxygen atmosphere → no further change afterward.

Spatiotemporal Consistency rubric:
level_1: The crucible or copper appears in a different location or amount between shots with no motion shown connecting them; the flame appears or disappears with no visible ignition or removal; the flask's shape distorts or breaks apart; or the room lighting jumps between very different brightness levels with no visible cause.
level_2: One clear break in physical continuity occurs: the crucible changes size or shape inconsistently between shots; the copper's amount changes (pieces merging or vanishing) without being shown mixing or breaking; the flame stays lit even while the crucible is not near it; or the flask switches between looking transparent and opaque with nothing passing in front of it to explain the change.
level_3: The crucible and copper keep a consistent size and shape as the flame heats them and as the crucible is lowered into the flask; the flask stays the same size and shape throughout; the flame stays attached to a visible source rather than floating free; lighting stays reasonably steady across the sequence, but one small flaw appears, such as a brief stutter as the crucible moves toward the flask, or a short flicker in the flame's brightness unrelated to any physical cause.
level_4: The flame shows natural, continuous flicker without freezing or repeating; the crucible's motion from the flame to inside the flask is smooth and unbroken; the copper shows no abrupt, unexplained brightness changes apart from what heating and the color change would cause; there is no visible warping or tearing of the crucible or flask edges; the only flaw left is something minor and non-core, such as a slightly uneven glow as the crucible passes the flask's mouth.
level_5: Every transition follows a clear, physically continuous order: copper is placed in the crucible → the crucible is heated by the external flame → the heated crucible is lowered into the oxygen flask → the copper darkens progressively → heating/observation ends; no motion repeats, skips, or plays out of order; the crucible and flask keep consistent proportions and lighting relative to each other throughout, with no sudden jumps in scale or perspective.