Domain: Natural Science — Chemistry
Target concept: Salt dissolves in water but is insoluble in oil.

Video generation prompt: Place two identical transparent glass containers side by side: the left one containing water and the right one containing clear edible oil. Add an equal small amount of salt to each container, and gently shake them.

Evaluation guide:
(i) Target concept: Differential solubility based on molecular polarity.
Minimum mechanism: Salt (ionic compound) must remain intact as solid crystals in oil (nonpolar medium) while dissociating into hydrated ions in water (polar medium), resulting in macroscopically invisible solute in water but persistent visible solids in oil.
(ii)Storyline: Frame 1–2: Static shot reveals two identical transparent containers side-by-side, left filled with water (lower surface reflectivity, softer meniscus), right with oil (higher gloss, tighter meniscus). Frame 3–4: Hand deposits identical white granular salt into each container: crystals land visibly on liquid surfaces. Frame 5–7: Both containers undergo synchronous gentle vertical shaking: liquid sloshes, crystals disperse briefly. Frame 8–10: Motion ceases; containers stabilize: left shows optically uniform clarity (no particles), right shows discrete white crystals settled at bottom or suspended. Contrast is stable, unoccluded, and viewable from fixed frontal perspective.

Manual:
Experimental Procedure
1. Place two identical transparent glass containers side-by-side: left with water, right with clear edible oil.
2. Add equal small amounts of white crystalline salt to both containers.
3. Gently shake both containers simultaneously.
Observation of Experimental Phenomena
After shaking and settling: salt fully disappears in water (clear solution), while white salt crystals remain visible and undissolved in oil (clear liquid with solid particles).
Summary of Experimental Principles
NaCl (table salt) is an ionic compound that dissociates into hydrated Na+ and Cl- ions in polar water via ion-dipole interactions, but remains an intact solid in nonpolar oil, which cannot stabilize separated ions.

Prompt Grounding rubric:
level_1: No transparent containers are visible, or only one container appears, or the two containers are not placed side by side; or water and oil are not visibly distinguishable as two separate clear liquids; or salt is never added to either container; or no shaking action is shown at all.
level_2: Two transparent containers stand side by side, but at least one setup element is wrong or missing: the left liquid is not identifiable as water (e.g., colored, cloudy, or absent), the right liquid is not identifiable as clear oil, salt is added to only one container, or shaking is applied to only one container.
level_3: Two matching transparent glass containers stand side by side, left holding clear water and right holding clear edible oil; a visually equal small pile of white crystalline salt is dropped into each container before both are gently shaken; placement, then salt addition, then shaking occur in that order for both containers.
level_4: Everything required for score 3 holds, and additionally: both containers stay upright and in place throughout; salt lands in both containers within the same brief interval rather than one much earlier than the other; the shaking applied to the water container matches the shaking applied to the oil container in rough speed and direction; no hand, label, or on-screen text blocks either container during salt addition or shaking.
level_5: Everything required for score 4 holds, and additionally: the two containers match each other in size, shape, and transparency; the water and the oil each look uniform and unclouded before salt is added; the two salt portions look like the same amount and grain size; each container is shaken only once, without repeated restarts; the camera holds one fixed, centered, front-on framing that keeps both containers visible from base to liquid surface throughout.

Scientific and Causal Correctness rubric:
level_1: No dissolution contrast appears at all, or the pattern is reversed/wrong: the salt visibly dissolves into the oil, the salt in the water stays as visible undissolved grains, both containers end up looking identical, or the salt changes color, melts, or otherwise reacts instead of simply dissolving or not.
level_2: At least one container shows an outcome inconsistent with real dissolution behavior: the oil turns cloudy or appears to dissolve the salt, or the water still shows floating or settled salt grains after shaking and settling; or both containers reach the same final appearance (e.g., both clear, or both full of visible grains).
level_3: After the shaking settles, the water container looks completely clear with no visible salt grains anywhere (fully dissolved), while the oil container still shows distinct white salt grains resting on the bottom or floating in it (undissolved); the contrast between clear water and grain-filled oil is plainly visible.
level_4: Everything required for score 3 holds, and additionally: the undissolved grains in the oil keep their crisp white crystalline look (no melting, smearing, or color change); the water stays glass-clear with no haze or floating specks; no salt residue clings visibly to the inner wall of the water container; the oil stays see-through everywhere except where a grain physically blocks the view.
level_5: Everything required for score 4 holds, and additionally: the salt grains in the oil keep sharp edges and a consistent bright-white color, without turning translucent or looking wetted; the water shows no cloudiness, streaking, or bubbles suggesting hidden undissolved material; the boundary between 'salt invisible in water' and 'salt visibly settled in oil' stays sharp and unchanging once shaking stops, with no drifting back and forth between dissolved- and undissolved-looking states.

Spatiotemporal Consistency rubric:
level_1: A container or the salt disappears and reappears with no visible motion carrying it there; the water or oil level jumps up or down between shots with no pouring or spilling shown; a container's shape suddenly warps or cracks apart; the lighting slams from bright to dark or back with no visible cause.
level_2: A container's position or tilt visibly jumps between two moments rather than sliding there smoothly (for example, shifting laterally by more than roughly 10% of its width between key frames); the salt seems to appear inside a container without traveling from the hand; the shaking motion reverses direction abruptly more than a couple of times in a jerky way; the shadows cast by the containers point a different way after a cut than before it, with nothing in the scene to explain the change.
level_3: The two containers stay put, side by side, without drifting or rotating on their own; the salt travels visibly from the hand into each container rather than appearing inside it; the shaking motion is smooth and repeats in the same back-and-forth pattern for both containers at roughly the same time; the shadows the containers cast keep pointing the same way and keep roughly the same darkness from start to finish; neither container bends, stretches, or is cut off by the frame edge.
level_4: Everything required for score 3 holds, and additionally: the hand never fully hides either container while adding salt or shaking; the motion of the falling salt and of the shaking looks continuous rather than skipping ahead in sudden steps; both containers sit on the same level surface, neither higher nor lower than the other; the liquid surfaces curve naturally at the container walls (meniscus) rather than looking perfectly flat or oddly bulging.
level_5: Everything required for score 4 holds, and additionally: the two containers never appear to shift sideways relative to each other as the view plays out, consistent with a locked-off camera; the falling salt arcs downward the way a dropped solid would, rather than drifting or floating in; the sloshing liquid settles down gradually after shaking stops rather than freezing instantly or sloshing forever; the container edges show no warping typical of a moving or zooming lens; the framing holds one fixed view with no zooming, panning, or tilting.