Domain: Natural Science — Chemistry
Target concept: Sodium acetate solution undergoes precipitation of minerals during cooling and crystallization (hot ice).

Video generation prompt: At room temperature, an oversaturated sodium acetate solution was transferred from a beaker into a glass dish containing a seed crystal.

Evaluation guide:
(i) Target concept: Nucleation-triggered phase transition in a metastable supersaturated solution.
Minimum mechanism: A physical seed crystal must be present *prior* to liquid contact; the solution must be liquid and optically clear *before* contact; crystallization must initiate *at the seed* and propagate *only after contact*; final state must be solid, opaque, and white.
(ii)Storyline: Frame 1–2: Static shot showing beaker (full of clear liquid) and glass dish (with distinct seed crystal inside), side-by-side, fixed viewpoint. Frame 3–4: Beaker tilts; liquid begins flowing toward dish. Frame 5: First droplet contacts seed crystal; no crystallization yet. Frame 6: Crystallization initiates *exactly at seed location*. Frame 7–9: Crystalline front expands continuously, uniformly, and irreversibly across liquid surface and depth. Frame 10: Entire poured volume is fully solidified, matte white, with no liquid remnants. Visibility constraint: Seed crystal must remain fully visible before, during, and immediately after first contact; no occlusion by hand, beaker, or splash.

Manual:
Experimental Procedure
1. A beaker holds a clear, supersaturated sodium acetate solution at room temperature.
2. A glass dish is placed beside it, containing a single visible seed crystal of sodium acetate.
3. The solution is poured steadily from the beaker into the dish, making direct contact with the seed crystal.

Observation of Experimental Phenomena
Upon contact with the seed crystal, the clear liquid rapidly transforms into an opaque white crystalline solid, propagating outward continuously from the seed until the entire poured volume is solidified.

Summary of Experimental Principles
Supersaturated sodium acetate solution is metastable at room temperature; introduction of a seed crystal provides nucleation sites, triggering instantaneous exothermic crystallization — commonly called “hot ice”.

Prompt Grounding rubric:
level_1: No beaker, no glass dish, and no seed crystal are visible; the sodium acetate solution is not shown in any container; no pouring or transfer action is depicted; none of the three core objects (beaker, glass dish, seed crystal) appears at all.
level_2: At least one core object is present (a beaker or a glass dish), but the seed crystal is absent; the transfer/pour action is missing or aimed at the wrong target (e.g., poured into empty air or into a different container); or the solution already looks crystallized before any contact happens.
level_3: A beaker of clear liquid, a glass dish, and a distinct seed crystal placed inside the dish before pouring are all present; a pour from beaker to dish takes place; however the seed crystal is not positioned where the poured stream actually lands, or the dish visibly slides or tips during the pour.
level_4: The beaker holds clear liquid, the glass dish sits still and shows a clearly visible seed crystal, and the pour is a continuous stream from beaker into dish; the seed crystal stays fully visible and undisturbed through the pour, and the poured liquid visibly reaches the seed crystal during or right after entering the dish; no unrelated objects or actions clutter the scene.
level_5: Level 4's correct setup holds, and additionally the beaker is never swapped for a different container and the seed crystal is never replaced by a different object partway through the clip, with exactly one beaker, one dish, and one seed crystal appearing throughout; no duplicate dish or extra seed crystal is introduced at any point.

Scientific and Causal Correctness rubric:
level_1: No crystallization ever occurs and the solution stays fully liquid throughout; or a solid forms without the poured liquid ever touching the seed crystal; or crystallization begins before the liquid even reaches the dish or the seed crystal.
level_2: Crystallization happens, but not because of the seed crystal: it starts on its own in the beaker, or spreads outward from the dish's rim rather than from the seed's location; or the resulting solid looks unlike sodium acetate (colored, feathery, or dendritic ice-like crystals) instead of a plain white mass; or the liquid changes color during the process.
level_3: Crystallization visibly starts right where the seed crystal sits once the poured liquid reaches it, and spreads outward from that point, turning the clear liquid into an opaque white solid; however the spreading is uneven: it stalls, skips patches, briefly seems to reverse, or extends beyond the dish onto the beaker or table.
level_4: Crystallization starts exactly at the seed crystal on contact and spreads outward continuously while staying fully within the dish; the entire poured volume becomes a uniformly opaque white solid with no leftover clear pockets and no new crystal patches starting away from the seed.
level_5: Level 4's correct nucleation-and-spread pattern holds, and additionally the finished solid is evenly opaque white from edge to edge with no clear or gel-like patches left behind, and it does not melt, sweat, or turn translucent again for the rest of the clip.

Spatiotemporal Consistency rubric:
level_1: The seed crystal, beaker, or dish is missing from a frame and then suddenly present again with no pour or hand motion to explain it; the dish or beaker jumps to a new position or orientation between frames; the room's lighting suddenly changes brightness or direction with no visible cause; the poured liquid moves in physically impossible ways (flowing upward, hanging in the air, or running backward into the beaker).
level_2: Smaller inconsistencies appear: the seed crystal's visible size or shape changes noticeably from one frame to the next with no explanation; the beaker's pouring lip and the dish drift out of alignment mid-pour; the shadow cast by the beaker or dish swings to a different direction with no corresponding change in the scene; the poured stream looks unnaturally stiff like a solid rod, or splashes far more violently than a thin liquid would.
level_3: The beaker, dish, and seed crystal each keep a steady size, position, and orientation across the video, and the light source and its shadows keep the same direction and brightness throughout; the pour itself looks like a real liquid, with no rigid stream and no impossible splattering; however, motion blur briefly hides the seed crystal right at the moment of contact, or the dish visibly wobbles for a moment relative to the beaker's spout.
level_4: Level 3's steady objects and lighting hold, and additionally there is no motion blur hiding the contact moment, no visible wobble or drift in dish or beaker, the beaker's spout stays lined up with the dish through the whole pour, and the seed crystal's position and apparent size stay visibly steady with no obvious drifting, resizing, or flicker between frames.
level_5: Level 4's clean contact and steady framing hold, and additionally the whole clip plays back with smooth, continuous motion and no stutter or dropped-looking frames; the beaker consistently sits in front of the background and the dish consistently sits in front of the seed crystal when it should, and no object's outline warps, bends, or loses its shape at any point.