Domain: Natural Science — Physics
Target concept: Melting rate of ice with the application of different ionic salts (calcium chloride vs. sodium chloride)

Video generation prompt: Two identical ice cubes are placed side by side; calcium chloride is sprinkled on the left one, and sodium chloride is sprinkled on the right one, then observed for several minutes.

Evaluation guide:
(i) Target concept: Differential melting rate of ice induced by colligative depression of freezing point, proportional to total dissolved ion concentration.
Minimum mechanism: Ice must be pure H₂O solid; salts must remain chemically intact upon contact (no reaction beyond dissolution); meltwater must be physically distinct from unmelted ice; no external heat source beyond ambient temperature; melting must proceed via surface dissolution and liquid film formation.
(ii)Storyline: Frame 0–2: Two identical ice cubes placed adjacent, stationary, dry surface. Frame 3–4: CaCl₂ applied to left cube (granular white deposit), NaCl applied to right cube (granular white deposit). Frame 5–10: Progressive appearance of transparent liquid on both cubes, with left cube exhibiting larger volume and earlier onset of runoff/pooling; liquid remains confined to vicinity of each cube; no mixing between left and right melt zones; fixed frontal viewpoint preserves unambiguous left/right spatial identity throughout.

Manual:
Experimental Procedure
1. Place two identical ice cubes side-by-side on a neutral-colored flat surface.
2. Sprinkle calcium chloride evenly on the left ice cube.
3. Sprinkle sodium chloride evenly on the right ice cube.
4. Observe for visual differences in melting behavior over time.
Observation of Experimental Phenomena
The left ice cube develops more visible liquid water (puddling, runoff) than the right ice cube within the observation period; both remain solid at start, and no other phase changes occur.
Summary of Experimental Principles
Calcium chloride lowers the freezing point of water more effectively than sodium chloride due to higher ion count per formula unit (Ca²⁺ + 2Cl⁻ vs. Na⁺ + Cl⁻), resulting in faster ice melting under identical conditions.

Prompt Grounding rubric:
level_1: No two ice cubes present; no ionic salts visible; no side-by-side placement; no identifiable left/right labeling or spatial distinction between treated cubes.
level_2: Two ice cubes present but not placed side-by-side; at least one ionic salt is visible (CaCl₂ or NaCl), but only one salt type applied, or both salts applied to same cube; no spatial differentiation (e.g., both cubes in same location, overlapping, or stacked).
level_3: Two identical ice cubes placed side-by-side in same scene and fixed viewpoint; calcium chloride visibly applied to left cube and sodium chloride visibly applied to right cube; both salts appear as granular white solids on respective ice surfaces; no mixing or cross-contamination between cubes.
level_4: All conditions for score 3 satisfied; additionally, the salt application occurs before any visible state change begins, and the left/right assignment remains unambiguous throughout (e.g., consistent labeling, persistent spatial orientation, no rotation or repositioning that obscures left/right identity).
level_5: All conditions for score 4 satisfied; additionally, the salt granules remain distinctly localized on their assigned ice cube surface (no migration, dripping, or pooling across the interface between cubes); spatial relationship (side-by-side) and left/right identity are continuously and unambiguously preserved from first frame of ice placement to final frame of observation.

Scientific and Causal Correctness rubric:
level_1: No state change observed in either ice cube; or both cubes melt identically (same rate/extent); or melting occurs without salt application; or non-ice objects melt or disappear.
level_2: Only one cube shows melting; or melting appears on wrong cube (e.g., left cube melts despite NaCl applied, or right melts despite CaCl₂ applied); or melting manifests as color change, bubbling, smoke, or phase separation inconsistent with ice-to-water transition.
level_3: Both cubes show partial melting (solid-to-liquid transition), but the left cube exhibits greater liquid accumulation (puddling, pooling, or runoff) than the right cube within the video duration; both remain solid at initiation and no evaporation, sublimation, or freezing reversal occurs.
level_4: All conditions for score 3 satisfied; additionally, the difference in melting extent is visually continuous and monotonic (i.e., left cube never shows less liquid than right cube at any point after salt application; no temporary reversal or equalization of melt extent).
level_5: All conditions for score 4 satisfied; additionally, the left cube shows *only* water (transparent, colorless liquid) accumulating on and around it, while the right cube shows *only* water (not slush, not opaque residue, not crystalline remnants mixed into liquid); no salt residue visibly dissolves into or contaminates the opposite cube’s meltwater.

Spatiotemporal Consistency rubric:
level_1: Ice cubes teleport, vanish, or reappear; sudden jumps in position, scale, or orientation; abrupt lighting changes (e.g., flash, blackout, color shift) unrelated to ambient conditions; structural breakage (e.g., ice shatters without cause, container fractures spontaneously).
level_2: One or both ice cubes deform unnaturally (e.g., bulge, stretch, liquefy without surface pooling); salt granules float mid-air or levitate; meltwater flows upward or violates gravity; background or container flickers or warps discontinuously.
level_3: All objects maintain stable position, shape, and scale; no object disappears/reappears mid-sequence; lighting remains consistent; meltwater forms and spreads only downward and outward from each ice cube base; no unnatural motion (e.g., jitter, warp, shear) in ice, salt, or liquid.
level_4: All conditions for score 3 satisfied; additionally, motion of meltwater is continuous and smooth (no teleportation of puddle edges, no frame-skipping of spread progression, no instantaneous full pooling); no temporal discontinuity (e.g., no jump-cut showing pre- and post-melt states without intermediate frames).
level_5: All conditions for score 4 satisfied; additionally, the spatial relationship (side-by-side) remains geometrically rigid: distance between cube centers stays constant; relative horizontal alignment (same baseline) is preserved; no parallax shift, zoom, or rotation that alters perceived adjacency or left/right ordering.