Domain: Natural Science — Atmospheric Science
Target concept: Supercooled bottled water freezes instantaneously when tapped.

Video generation prompt: A transparent sealed plastic bottle containing supercooled pure water is placed on a cold tabletop, and one hand gently taps the bottle.

Evaluation guide:
(i) Target concept: Instantaneous solidification of metastable supercooled liquid via mechanical nucleation.
Minimum mechanism: Water must be pure, still, and below 0°C but above homogeneous nucleation threshold (~−40°C); bottle must be smooth, clean, and sealed to prevent spontaneous freezing; tap must deliver localized energy sufficient to overcome nucleation barrier without breaking container.
(ii)Storyline: [Phase 1: Stable State] Bottle sits motionless on cold tabletop; water is fully liquid, transparent, and quiescent: no visible ice, bubbles, or convection. [Phase 2: Perturbation] Hand enters frame and makes direct, brief contact with bottle wall, inducing micro-deformation but no displacement. [Phase 3: Nucleation & Propagation] Within <0.5s of contact end, crystalline ice appears at the tap site and spreads as a branching network of ice crystals across the entire water volume, coexisting with residual liquid. [Phase 4: Final State] The visible water column is filled with a fine, translucent ice-crystal slush (not a fully solid block); residual liquid visible between crystals is expected and correct; bottle remains structurally intact: no melting back, cracking, or effervescence. Perspective: Fixed frontal or 3/4 view; full bottle and hand contact zone must remain fully in-frame and in-focus throughout; no occlusion of water interior during propagation.

Manual:
Experimental Procedure
1. Place a sealed transparent plastic bottle filled with pure, clear liquid water on a cold, flat tabletop.
2. Ensure bottle is motionless and upright.
3. Gently tap the side or shoulder of the bottle with one bare hand.
Observation of Experimental Phenomena
Immediately after tapping, ice nucleates at the contact point and rapidly propagates through the water, filling the visible volume with a fine, translucent network of ice crystals — an ice-water slush rather than a fully solid block, since the limited amount of supercooling cannot release enough latent heat to freeze all the liquid — with no melting back observed during the recording.
Summary of Experimental Principles
Supercooled water remains liquid below 0°C due to lack of nucleation sites; mechanical disturbance (tap) provides energy and imperfection to trigger instantaneous heterogeneous nucleation and rapid solidification. Because the heat released as ice forms is limited by how deeply the water was supercooled, only a fraction of the water freezes, leaving a slush of ice crystals coexisting with liquid water rather than a solid block.

Prompt Grounding rubric:
level_1: No sealed transparent plastic bottle of water is shown, no cold tabletop is visible, and no hand or tapping action appears; the scene bears no resemblance to a bottle-tapping setup.
level_2: A transparent bottle appears but it is open/unsealed or made of glass/metal instead of plastic; the water is missing, already frozen, or visibly cloudy; the tabletop is absent or looks warm/cluttered rather than a plain cool surface; or a hand is present but never touches the bottle.
level_3: A sealed, transparent plastic bottle of clear water rests on a flat, plain, cool-toned tabletop, and a hand enters the frame and touches the bottle, but the touch is not clearly aimed at the bottle's side or shoulder, or the contact looks glancing rather than a deliberate tap.
level_4: Everything in the 3-point description holds, and in addition the hand delivers an unmistakable, brief, direct tap to the side or shoulder of the bottle (a visible flinch or rebound of the bottle wall confirms contact); the bottle stays upright and does not slide or tip before or during the tap; no unrelated objects or actions compete for attention.
level_5: Everything in the 4-point description holds, and in addition the tap lands while the bottle is completely still on the tabletop (no sliding, tipping, or repositioning right before contact); the bottle stands vertical or nearly so; the hand is bare with fingers clearly visible, and the exact spot where skin meets bottle is plainly visible on camera (its location on the bottle body is not otherwise restricted).

Scientific and Causal Correctness rubric:
level_1: No freezing happens at all and the water stays liquid throughout; or ice is already visible in the bottle before the tap; or nothing changes until more than about a second after the tap ends.
level_2: Freezing happens but only in an isolated pocket (e.g., just at the bottom or in a single streak) rather than spreading from the tap point; freezing starts before the tap or keeps forming for more than about a second after the tap ends; the frozen part looks milky/opaque rather than the fine, branching crystalline look of real ice; or the bottle already shows frost or dew on its outside before the tap, hinting it was never truly supercooled.
level_3: Freezing begins in the same shot right after the hand contact ends; a visible ice front spreads outward from the tap point; the newly frozen region has the fine, feather-like, translucent look of an ice-crystal network (not solid milky ice), with liquid still clearly present around and beyond it; nothing outside the tap (heat, shaking, pouring) triggers the freezing.
level_4: Everything in the 3-point description holds, and in addition the ice front keeps advancing without stalling or restarting and spreads through at least half of the visible water column within the same shot; once formed, the crystalline region does not melt back or re-liquefy while still on camera; the water that has not yet frozen stays clear and calm (no swirling or bubbling).
level_5: Everything in the 4-point description holds, and in addition the branching ice front reaches every part of the visible water column, leaving the bottle's interior filled with a fine translucent ice-and-liquid slush (residual liquid visibly threaded between crystals is expected and correct, since a single tap cannot freeze the entire bottle into solid ice); the ice front starts spreading essentially the instant the tap ends, with no perceptible pause.

Spatiotemporal Consistency rubric:
level_1: The bottle jumps to a different position or orientation between frames; the hand appears or disappears abruptly instead of entering the frame naturally; the room lighting swings violently partway through; the tabletop surface warps or disappears; the bottle cracks open or leaks; or the shot cuts/jumps and breaks continuity.
level_2: The bottle slides or rotates more than about 15 degrees with no visible cause; the hand's motion looks jerky or is clearly interpolated rather than a natural tap; the shadow cast by the hand or bottle swings to a different direction or disappears during contact; or condensation appears and disappears on the bottle's outside between frames.
level_3: The bottle stays in the same place and orientation on the tabletop the whole time; the hand moves into frame smoothly and reaches the bottle without a sudden jump in speed; the tabletop's lighting and the bottle's cast shadow keep the same brightness and direction from before the tap through after it; the bottle and hand keep their shape (no warping or stretching); nothing on screen behaves in a physically implausible way.
level_4: Everything in the 3-point description holds, and in addition the hand's tapping motion looks physically natural: contact produces a small, believable dent or flex in the bottle wall that springs back right away; frame-to-frame flicker or stutter is absent; the background stays still and in focus; the camera itself does not appear to shift or drift.
level_5: Everything in the 4-point description holds, and in addition the bottle's momentary flex lines up with exactly where and when the hand makes contact; the hand's recoil matches the bottle's rebound; the hand's motion blur looks consistent with a normal human tap speed (not too fast or smeared); the camera's framing, focus, and depth of field stay the same throughout; and there is no visible flash or abrupt color shift between frames.