Domain: Natural Science — Earth Science
Target concept: Mix calcium chloride solution with sodium carbonate to produce calcium carbonate.

Video generation prompt: Two transparent beakers contain calcium chloride aqueous solution and sodium carbonate aqueous solution, respectively; one of the solutions is slowly added to the other.

Evaluation guide:
(i) Target concept: Precipitation via double displacement reaction in aqueous solution.
Minimum mechanism: Both reactants must be dissolved ionic compounds; product CaCO₃ must be thermodynamically insoluble under ambient conditions and manifest as discrete solid phase distinct from solvent.
(ii)Storyline: [Frame 0–2] Two labeled, transparent beakers side-by-side, each holding still, colorless liquid; [Frame 3–5] Pouring begins: stream emerges from lip of source beaker and contacts surface of liquid in receiving beaker; [Frame 6–8] White precipitate appears *only* in receiving beaker, increasing in density as pouring continues; [Frame 9–10] Final state shows uniform cloudy-white suspension with no settling or clearing; all events occur in fixed frontal view with full beaker visibility and no cuts or perspective shifts.

Manual:
Experimental Procedure
1. Place two identical transparent beakers side-by-side.
2. Fill left beaker with calcium chloride aqueous solution (colorless).
3. Fill right beaker with sodium carbonate aqueous solution (colorless).
4. Slowly pour solution from one beaker into the other.
Observation of Experimental Phenomena
A white, powdery precipitate forms immediately in the receiving beaker, turning the mixture cloudy and opaque while remaining colorless except for the white solid.
Summary of Experimental Principles
Calcium chloride and sodium carbonate undergo double displacement: CaCl₂(aq) + Na₂CO₃(aq) → CaCO₃(s)↓ + 2NaCl(aq). Calcium carbonate is insoluble and precipitates as a white solid.

Prompt Grounding rubric:
level_1: No two transparent beakers visible; no calcium chloride solution or sodium carbonate solution present; no pouring action shown; no side-by-side container arrangement; no single continuous scene showing both solutions before mixing.
level_2: Two containers present but not both transparent beakers; at least one solution is absent or mislabeled (e.g., colored liquid, wrong container type); pouring action is absent or performed between non-beaker vessels; spatial arrangement is not side-by-side or same scene.
level_3: Two transparent beakers are present and side-by-side in same scene; both contain colorless aqueous solutions; one beaker is clearly designated as calcium chloride solution and the other as sodium carbonate solution (via on-screen text label OR consistent labeling convention used throughout); pouring action occurs from one beaker into the other; direction is visible and unambiguous.
level_4: All 3-point conditions satisfied; additionally: labels (if used) are legible and correctly spelled; pouring begins from the correct source beaker (i.e., either CaCl₂ → Na₂CO₃ or Na₂CO₃ → CaCl₂, both valid per prompt); no extraneous objects or actions interrupt the demonstration; viewpoint remains fixed and includes full beaker bases and liquid levels throughout.
level_5: All 4-point conditions satisfied; additionally: both beakers maintain identical physical appearance (shape, size, transparency, rim geometry); liquid surfaces remain still before pouring and show realistic meniscus; pouring motion is smooth, continuous, and terminates before overflow; no visual artifacts, occlusions, or frame drops; labels (if present) appear simultaneously with first beaker visibility and persist until end.

Scientific and Causal Correctness rubric:
level_1: No precipitate formation observed; final mixture remains fully transparent and homogeneous; no visible state change; color of solution changes (e.g., turns blue, yellow, or opaque without white solid); solid appears but is not white or not granular/powdery.
level_2: Precipitate appears but is not white; or precipitate appears only after delay >2 seconds post-pouring (visually inconsistent with reaction kinetics); or precipitate forms but dissolves immediately; or precipitate forms in source beaker instead of receiving beaker; or cloudiness occurs without discrete solid particles.
level_3: White precipitate appears exclusively in the receiving beaker after pouring begins; precipitate is granular or powdery (not gelatinous, crystalline spikes, or film-like); mixture becomes visibly cloudy/milky; no color change beyond whitening; no dissolution or disappearance of precipitate during video.
level_4: All 3-point conditions satisfied; additionally: precipitate forms progressively, initial fine suspension visible within first half of pouring motion; cloudiness intensifies continuously as pouring proceeds; no abrupt “flash” appearance; no secondary phenomena (e.g., bubbling, temperature-induced shimmer, layer separation).
level_5: All 4-point conditions satisfied; additionally: precipitate remains uniformly suspended (no rapid settling during video); no floating clumps or surface scum; no residual clarity at top or bottom; opacity is consistent across entire liquid column; no discoloration (e.g., yellow tint, gray hue) anywhere in mixture.

Spatiotemporal Consistency rubric:
level_1: Beakers teleport between frames; liquid level jumps discontinuously; pouring stream disappears/reappears mid-motion; light/shadow shifts abruptly between frames; beaker edges warp or distort; background changes inconsistently.
level_2: One beaker rotates or shifts position significantly between pre- and post-pour frames; pouring stream exhibits unnatural segmentation (e.g., broken droplets, stuttering motion); meniscus flattens or inverts unrealistically; shadow moves opposite to light source; container base disconnects from surface.
level_3: Both beakers remain stationary and upright; pouring stream is continuous and connects source beaker lip to receiving beaker liquid surface; liquid surface in receiving beaker rises smoothly and consistently; no structural warping, edge flickering, or inter-frame occlusion of beaker walls or labels.
level_4: All 3-point conditions satisfied; additionally: meniscus curvature remains physically plausible before/during/after pouring; no parallax shift between beaker positions across frames; no lighting discontinuity (e.g., specular highlight vanishes then reappears); no temporal reversal or out-of-order frame presentation.
level_5: All 4-point conditions satisfied; additionally: liquid surface deformation upon impact is subtle but visible (small ripples radiating from entry point); no motion blur that obscures beaker rims or precipitate onset; no jitter, zoom, or focus breathing; all elements maintain consistent scale and perspective throughout.