Domain: Natural Science — Chemistry
Target concept: Zinc metal is placed in a copper sulfate solution (color change and deposition of copper)

Video generation prompt: Place a clean zinc strip into a transparent glass beaker containing blue copper(II) sulfate solution, and immerse it completely.

Evaluation guide:
(i) Target concept: Single displacement redox reaction where solid zinc reduces aqueous Cu²⁺ to solid copper while oxidizing to Zn²⁺.
Minimum mechanism: Zinc must be in direct, continuous contact with copper(II) sulfate solution; electron transfer must occur at the solid-liquid interface; copper nucleation must initiate on zinc surface (not homogeneous precipitation); solution color change requires sufficient Cu²⁺ depletion to reduce absorbance in visible range (600–800 nm).
(ii)Storyline: [Phase 1: Setup] Clean zinc strip held above beaker containing uniform blue solution; no deposit, no color change. [Phase 2: Immersion] Strip descends continuously and fully enters solution; contact initiates at liquid surface, no splash or rebound. [Phase 3: Reaction onset] Within 1–2 seconds post-immersion, localized reddish-brown deposit appears at bottom of submerged strip. [Phase 4: Propagation] Deposit spreads continuously upward along submerged length; simultaneously, entire visible solution volume lightens in blue saturation. [Phase 5: Steady state] Deposit fully covers submerged surface; solution remains stably paler blue/greenish-blue; no gas, dissolution, or secondary effects. Perspective: Fixed frontal view, centered on beaker, full strip and liquid column visible; no occlusion; lighting enables clear discrimination of strip surface texture, deposit color, and solution hue.

Manual:
Experimental Procedure
1. Hold a clean, dull gray-silver zinc strip vertically.
2. Lower it steadily into a transparent glass beaker filled with clear blue copper(II) sulfate solution.
3. Ensure the entire strip is fully submerged below the liquid surface.
Observation of Experimental Phenomena
- The blue color of the solution gradually fades to paler blue or greenish-blue.
- A reddish-brown solid deposits uniformly on the submerged surface of the zinc strip.
Summary of Experimental Principles
Zinc is more reactive than copper; it displaces Cu²⁺ ions from solution, forming zinc sulfate and elemental copper: Zn(s) + CuSO₄(aq) → ZnSO₄(aq) + Cu(s).

Prompt Grounding rubric:
level_1: No zinc strip appears; no transparent glass beaker is shown; no blue liquid is visible; the strip is never lowered into any container.
level_2: At least one core prop appears (a metal strip, a beaker, or a blue liquid) but something is wrong: the strip is corroded/coated rather than clean, the container is opaque or clearly not glass, the liquid is not blue, or the strip sits beside the beaker instead of going into it.
level_3: A clean metallic strip is lowered into a transparent container holding a blue liquid, and the strip ends up fully covered by the liquid; the zinc strip, the glass beaker, and the copper sulfate solution are all present and correctly identifiable, though the strip's gray sheen, the beaker's glass-like appearance, or the completeness of submersion is only approximately right.
level_4: The strip clearly matches zinc's dull gray sheen (not shiny like aluminum or reddish like copper), the beaker is thin-walled, cylindrical, and glass-like with no plastic look, the liquid fills the beaker to a plausible level, the strip is entirely submerged with no exposed dry portion, and no extra items (gloves, labels, other containers) clutter the shot.
level_5: In addition to level 4, the strip descends into the beaker in one unbroken downward motion with no pause, lift, or repositioning, then stays still and fully submerged for at least two seconds within the clip, the camera holds one fixed framing with no zoom or refocus, and the background stays plain so the strip and beaker remain the visual focus.

Scientific and Causal Correctness rubric:
level_1: No color change occurs in the liquid and no deposit forms on the strip: the blue solution and the strip's surface look the same at the end of the clip as at the start.
level_2: Either the liquid changes to a color other than a paler blue/greenish tint (e.g., it turns purple, yellow, or clear), or a deposit forms in the wrong color (black, white, or shiny silver instead of reddish-brown), or the deposit shows up on the beaker's wall/bottom instead of on the strip, or the strip appears to dissolve or bubble without any deposit forming.
level_3: The blue liquid visibly becomes lighter/less saturated and a reddish-brown deposit appears on the submerged part of the strip; but either the deposit shows up before the strip is fully submerged, or it only covers a patch/tip of the strip rather than a continuous stretch, or the liquid's fading looks uneven (e.g., paler only right next to the strip).
level_4: The whole visible volume of liquid loses blue saturation and trends toward a pale or greenish-blue, and the reddish-brown deposit covers the entire submerged length of the strip continuously and stays stuck to the surface (not flaking or floating), with no gas bubbles or cloudiness competing for attention, and the deposit clearly appears only after the strip contacts the liquid.
level_5: The deposit appears only once the strip is fully submerged (never during the lowering motion), spreads continuously and evenly from the bottom of the strip upward with no gaps, and the liquid's color fade begins after the deposit starts forming and then progresses evenly through the whole visible volume; both changes hold steady with no flicker or reversal through the end of the clip.

Spatiotemporal Consistency rubric:
level_1: The strip jumps straight into the beaker with no travel shown in between; the liquid disappears or appears mid-clip; the beaker's shape breaks or deforms; the lighting flips from bright to dark in a single frame; the strip rotates by more than a quarter turn with no visible cause.
level_2: The strip's entry into the liquid shows an obvious jump-cut or skip; the liquid's surface bounces rigidly or ripples unnaturally slowly; a shadow's position jumps between frames; the beaker's outline flickers or warps intermittently; the strip's descent looks jerky, stopping and starting instantly rather than moving smoothly.
level_3: The strip's downward path shows a little jitter but never breaks continuity; the reflection on the liquid surface is slightly uneven but never discontinuous; the shadow sits a bit off from where the light source would place it, but consistently so; the beaker keeps its shape and clarity aside from minor distortion right at its edges; the strip's motion doesn't visibly slow down as it meets the liquid.
level_4: The strip moves smoothly downward and visibly slows as it meets the liquid surface; the beaker stays fixed in the frame with no stretching or flickering transparency; the liquid surface stays level and calm except for gentle contact with the strip; the shadow's direction and softness stay the same throughout; there is no visible tearing, doubling, or strobing of any object.
level_5: The strip's descent looks physically natural (speeding up under gravity, then slowing smoothly as it meets the liquid), the surface rises slightly and evenly around the strip with no splash or bounce-back, and the surface settles into a calm, continuous curve almost right away; the lighting's brightness, direction, and color stay visibly the same for the strip, beaker, and liquid across the whole clip.