Domain: Natural Science — Physics
Target concept: Melting rate of wax on a warm surface under conditions with and without airflow

Video generation prompt: Place two identical wax droplets on a heated metal plate; the fan continuously blows air toward the right wax droplet, while the left wax droplet is in still air, and continuous recording is performed.

Evaluation guide:
(i) Target concept: Convective enhancement of conductive heat transfer alters phase-change kinetics in solids.
Minimum mechanism: Wax must be thermally sensitive near its melting point; metal plate must be above melting temperature; airflow must be laminar and directed; ambient pressure and humidity must permit evaporative cooling to be negligible relative to convection.
(ii)Storyline: Frame 0–2s: Two identical solid wax droplets sit side-by-side on heated plate; fan is stationary or just starting. Frame 2–6s: Right droplet begins losing dome shape, edges soften and spread outward; left droplet remains convex with crisp perimeter. Frame 6–10s: Right droplet forms continuous liquid pool with smooth meniscus; left droplet still shows central elevation and dry-looking surface; the fan keeps running and stays aimed only at the right droplet throughout (a visible dust or smoke trail drifting toward the right droplet is optional supporting evidence, not a requirement). Perspective: Fixed frontal, eye-level view; full plate and both droplets always in frame; no occlusion; lighting uniform and top-down to preserve shadow consistency.

Manual:
Experimental Procedure
1. Place two identical wax droplets side-by-side on a uniformly heated horizontal metal plate.
2. Position a fan so its airflow is directed continuously and exclusively toward the right droplet.
3. Begin continuous recording for 10 seconds.
Observation of Experimental Phenomena
The right wax droplet melts faster and spreads into a flatter, wider liquid pool; the left wax droplet retains its original dome shape longer and shows slower or minimal spreading.
Summary of Experimental Principles
Airflow increases convective heat transfer from the plate to the wax surface, accelerating melting. Still air limits heat transfer to conduction and radiation only, resulting in slower phase change.

Prompt Grounding rubric:
level_1: The heated metal plate is absent, the two wax droplets are missing or merged into a single droplet, or the fan is nowhere in frame; the footage is a static image or a series of disconnected cuts rather than one continuous shot of the plate.
level_2: The heated plate and both wax droplets are visible, but the fan is either missing or clearly not pointed at either droplet (e.g., aimed away from the plate, or sitting unplugged in the background); or the two droplets are shown one behind the other, or in separate shots, rather than level with each other on the same plate.
level_3: The heated plate, both wax droplets, and the fan are all visible at the same time for the whole clip; the two droplets sit level with each other on the plate, one on the left and one on the right; the fan's body is oriented toward the right-hand droplet.
level_4: Everything required for score 3 holds, and the fan's blades are visibly turning (or its housing shows motor vibration) for the entire clip, giving clear evidence it is actively running and aimed only at the right droplet; a visible airflow tracer such as dust or smoke drifting toward the right droplet is acceptable supporting evidence but is not required.
level_5: Everything required for score 4 holds, and the fan keeps blowing toward the right droplet only (never swiveling toward the left droplet and never switching off) from the first frame to the last, while the left droplet is never touched by any visible airflow cue.

Scientific and Causal Correctness rubric:
level_1: Neither wax droplet shows any softening, slumping, or shape change; both stay identical solid domes for the whole clip, with no visible difference between the fan-blown droplet and the still-air droplet.
level_2: One or both droplets soften or melt, but the two droplets change at visually indistinguishable rates (for example both slump by the same amount at the same time), so the airflow produces no observable difference between them.
level_3: The right (fan-blown) droplet visibly softens and begins spreading into a puddle earlier or faster than the left (still-air) droplet; the left droplet keeps its rounded dome shape noticeably longer than the right.
level_4: Everything required for score 3 holds, and the right droplet's spreading keeps progressing forward without re-forming a dome or hardening back up, while the left droplet shows no comparable spreading or flattening within the same stretch of time.
level_5: Everything required for score 4 holds, and by the end of the clip the right droplet has become a smooth, cohesive puddle with a rounded, wet-looking edge, while the left droplet still shows a dry, sharply defined solid edge; the two droplets' phases are never ambiguous or interchangeable at any point in the video.

Spatiotemporal Consistency rubric:
level_1: Either wax droplet disappears or appears abruptly mid-clip, the plate's orientation jumps between frames, a shadow flips to the opposite side with no change in the light, or the plate or fan visibly breaks apart or fuses together unrealistically.
level_2: Two or more of the following happen, or one of them happens more than once: the same droplet flickers in and out of view, the fan's blades visibly reverse direction or stutter, or the plate's surface texture warps momentarily. An isolated one-time glitch does not qualify for this level.
level_3: None of the level-1 or level-2 flaws occur: no object disappearance, no orientation jump, no shadow flip, and no repeated flicker, stutter, or warp; the plate, droplets, and fan hold their positions, the fan's blades (if visible) spin steadily in one direction, and any droplet spreading moves outward gradually rather than jumping between states.
level_4: Everything required for score 3 holds, and the motion of the fan blades and the spreading wax is smooth from frame to frame with no stutter or strobing, and the shadows cast by the plate, droplets, and fan stay on the same side and the same relative length throughout, consistent with one unmoving light source.
level_5: Everything required for score 4 holds, and no droplet or plate edge flickers, doubles, or blurs in a way inconsistent with how fast it's moving, so the plate, both droplets, and the fan look like one continuous physical scene from the first frame to the last.