Domain: Natural Science — Chemistry
Target concept: Electroplating copper onto a metal key in solution

Video generation prompt: A transparent container containing a blue copper sulfate solution, with a metal key and a copper strip inside, both connected by wires to a direct current power supply; the power supply is turned on and operating continuously.

Evaluation guide:
(i) Target concept: Electrodeposition of copper onto a cathodic substrate (the key) via direct current electrolysis in aqueous CuSO₄, together with continuous anodic dissolution of the copper strip.
Minimum mechanism: Cu²⁺(aq) + 2e⁻ → Cu(s) must occur at the key (cathode); at the same time the copper strip (anode) continuously oxidizes, Cu(s) → Cu²⁺(aq) + 2e⁻, at a rate matched to cathodic deposition by Faraday's law: this is why the CuSO₄ solution's blue color and concentration stay constant during continuous operation; the power supply must provide sustained DC current; the solution must remain homogeneous; no competing redox reaction (e.g., H₂ or O₂ evolution) may dominate or distort the visual outcome.
(ii)Storyline: Frame 1–2: Static shot showing transparent container filled with uniform blue solution, metal key and copper strip submerged side-by-side, wires attached to both, leading to a DC power supply in OFF state. Frame 3: Power supply transitions to ON state (visual indicator activates). Frame 4–10: Continuous view showing progressive, exclusive appearance of a reddish-brown deposit on the key's surface (initiating at the electrode-solution interface and spreading contiguously), while solution hue, clarity, and electrode positions remain invariant; the copper strip shows no new deposit forming on it, and may thin only slightly and gradually over the recording as it continuously supplies Cu²⁺ ions to the solution; viewpoint is fixed frontal, fully framing container, electrodes, wires, and power supply without occlusion or zoom.

Manual:
Experimental Procedure
1. Place a clean metal key and a copper strip side-by-side inside a transparent container.
2. Fill container with aqueous copper sulfate solution until both electrodes are fully submerged.
3. Connect key to negative terminal and copper strip to positive terminal of a DC power supply using insulated wires.
4. Turn on power supply and maintain continuous operation.
Observation of Experimental Phenomena
- The blue color of the copper sulfate solution remains unchanged.
- A reddish-brown solid deposit forms exclusively on the surface of the metal key.
- No deposit forms on the copper strip or container walls.
- The copper strip (anode) continuously oxidizes and may thin gradually over time as it supplies Cu²⁺ ions to solution; any change over the video's short duration is expected to be modest rather than a sudden loss of shape or a coating change.
Summary of Experimental Principles
Electroplating occurs via electrolysis: Cu²⁺ ions in solution gain electrons at the cathode (key), reducing to metallic copper and depositing on its surface; the copper strip acts as the anode, continuously oxidizing (Cu → Cu²⁺ + 2e⁻) at a rate matched to cathodic deposition per Faraday's law — this ongoing anodic dissolution is precisely what keeps the CuSO₄ solution's Cu²⁺ concentration and blue color constant during continuous operation.

Prompt Grounding rubric:
level_1: No transparent container is visible; no blue liquid is present; the metal key and copper strip are not both present in the same scene; no wires connect the electrodes to a power supply; no power supply unit is visible at all.
level_2: A transparent container holds a colored liquid that is not blue; or the container holds blue liquid but only one of the two electrodes (key or copper strip) is present; or wires are present but do not connect both electrodes to a power supply; or a power supply is shown but gives no indication of being turned on (no indicator light, no label suggesting operation).
level_3: A transparent container with blue liquid is present; both the metal key and the copper strip are inside the container; wires connect each electrode to a power supply unit; the power supply is visibly present and designed as a DC source, but nothing in the frame shows it is turned on (no illuminated indicator, no 'ON' label, no active display).
level_4: Everything in score 3 holds, and the power supply additionally shows a clear operational sign (an illuminated ON indicator, a visible 'ON' label, or a display showing voltage/current), and every wire visibly and continuously connects an electrode terminal to a power-supply terminal with no gaps or floating ends.
level_5: Everything in score 4 holds, and the spatial arrangement matches the posted_prompt: the key and copper strip sit side by side, fully submerged in the blue solution; wires run from each electrode to two separate terminals on the same DC power supply (color-coding or labeling of the terminals is not required); the power supply sits in a fixed, sensible position relative to the container; nothing extraneous blocks the setup; the camera holds one continuous fixed frontal view showing the full container, electrodes, wires, and power supply.

Scientific and Causal Correctness rubric:
level_1: The solution is not blue, the key is not bare metallic gray/silver, or the copper strip is not reddish-brown; no reddish-brown deposit ever forms on the key; the video shows no color, gas, or surface change consistent with copper electrodeposition at all.
level_2: The blue solution looks turbid, milky, or separated into layers rather than uniform; the key already looks coated or discolored before the power supply turns on; the copper strip looks oxidized to green or black instead of its normal reddish-brown; or the reddish-brown deposit forms on the copper strip instead of the key, or looks white/gray rather than reddish-brown.
level_3: The CuSO₄ solution is uniformly blue and clear; the key starts out bare and metallic gray/silver; the copper strip starts out reddish-brown and metallic; once the power supply turns on, a reddish-brown deposit appears on the key's submerged surface; no such deposit appears on the copper strip; the solution shows no bubbling, fading, or floating particulate matter.
level_4: Everything in score 3 holds, and the deposit on the key looks like a continuous, adherent metallic copper layer rather than flaky, powdery, or crystalline material; the blue solution's color and clarity stay the same from start to finish; the copper strip may show at most a slight, gradual dulling or thinning consistent with its role as the anode supplying Cu²⁺ to the solution; this is expected and should not be penalized, as long as it is not a sudden, large-scale loss of material or shape.
level_5: Everything in score 4 holds, and the deposit's growth is tied to the power supply turning on: it begins only after the ON indicator activates, starts at the face of the key nearest the copper strip, and spreads across the submerged area from there; no deposit appears on the wires, container walls, or above the liquid surface; the solution's blue color and transparency stay uniform throughout the container, consistent with the copper strip continuously resupplying Cu²⁺ ions to solution as it slowly oxidizes.

Spatiotemporal Consistency rubric:
level_1: The key, copper strip, or wires vanish and reappear, or jump to new positions with no motion shown between frames; the container's shape warps or breaks apart; the shadow beneath the container flips to the opposite side or disappears and comes back; the power-supply indicator switches on and off erratically instead of transitioning once.
level_2: The container shows warping or refraction that doesn't match real glass or plastic; a wire hangs rigid and unsupported as if frozen in place, or floats away from where it's attached; the key or copper strip rotates or shifts position with no visible cause; a bright mirror-like highlight appears on the key's surface when it should look like a duller, matte metal; the liquid surface ripples even though nothing in the scene is disturbing it.
level_3: The key, copper strip, wires, container, and power supply keep the same size, shape, and position relative to each other across the video; the container stays upright and rigid; both electrodes stay fully submerged and still; the wires stay taut along the same path; the shadow on the tabletop keeps the same direction and softness from frame to frame; nothing flickers, duplicates, or breaks apart.
level_4: Everything in score 3 holds, and the power-supply indicator's transition from off to on is a gradual brightening or a single clean switch rather than an instant flash; the reddish-brown deposit on the key grows visibly across at least two consecutive frames rather than appearing all at once; the depth each electrode sits at and the liquid's surface level stay the same from one frame to the next.
level_5: Everything in score 4 holds, and the distance between the key and the copper strip never changes; the wires never cross through each other unnaturally; the container's edges stay sharp and undistorted; the liquid surface stays flat and level; the camera framing never drifts; the deposit only ever grows across the key's surface: it never shrinks, reverses, or jumps to a new location.