Domain: Natural Science — Physics
Target concept: Comparison of Metal Plates Cooled in Still Air and Those Cooled by Forced Airflow

Video generation prompt: Two identical hot metal plates are placed side by side, with wax droplets on their surfaces. After the heating is stopped, one plate cools in still air, while the other cools under a continuous airflow from a desk fan. The cooling processes of both plates are recorded.

Evaluation guide:
(i) Target concept: Convective cooling rate depends on airflow velocity.
Minimum mechanism: Both plates' wax droplets begin the recording molten (glossy, flattened) because the plate surfaces are still above the wax's melting/softening point right after heating stops. Forced convection over the fan-facing plate has a higher heat-transfer coefficient, so that plate's surface temperature falls below the wax's melting/softening point sooner, letting its wax finish solidifying (turning matte, rounded, and static) earlier in the clip. The still-air plate loses heat more slowly by natural convection and conduction, so it stays above the wax's melting/softening point longer, keeping its wax visibly glossy/molten (or only partway through solidifying) for a longer stretch of the recording.
(ii) Storyline: [Frame 0] Heating has just stopped; both plates are hot and each holds wax droplets that look glossy and flattened (not yet solidified); the fan is off. [Frames 1-N] The fan turns on and blows continuously at only one plate (the forced-air plate); that plate's wax gradually dulls, rounds up, and stops changing appearance well before the recording ends; the wax on the other plate stays glossy/flattened, or is only beginning to round up and dull, for a clearly longer stretch of the clip. [Visibility constraint] Full frontal view, fixed camera, no occlusion; both plates and all wax droplets fully visible throughout; the fan must be shown as an identifiable mechanical device (housing plus rotating blades), not an abstract wind symbol.

Manual:
Experimental Procedure
1. Place two identical hot metal plates side-by-side on a non-conductive surface.
2. Apply identical wax droplets onto the center of each plate surface while the plates are still hot, so the wax starts out molten.
3. Stop heating both plates simultaneously.
4. Immediately direct a desk fan to blow continuously onto only one plate; leave the other in still air.
Observation of Experimental Phenomena
The wax droplets on the forced-air plate stop spreading and visibly dull and round up into a fixed solid shape sooner than the wax droplets on the still-air plate, which stay glossy, flattened, and slow to firm up because that plate stays above the wax's melting/softening temperature for longer.
Summary of Experimental Principles
Forced airflow increases the convective heat-transfer coefficient, so the fan-facing plate's surface temperature drops below the wax's melting/softening point sooner, letting its wax finish solidifying earlier. Still air relies on slower natural convection and conduction, so that plate's surface stays above the wax's melting/softening point longer, delaying when its wax solidifies and keeping it glossy/molten-looking longer into the recording.

Prompt Grounding rubric:
level_1: Two metal plates are not shown positioned next to each other; wax droplets are absent from the plate surfaces; no desk fan appears anywhere in the shot; the video never shows a moment when active heating (flame, glowing burner, hot element) has already ceased.
level_2: Two plates are shown but are not near each other in the frame; wax droplets sit on only one plate or on neither; a desk fan is visible but its blades are not oriented toward either plate; whether heating has stopped before the visible cooling begins is unclear.
level_3: Two visually identical metal plates sit close together in the same frame; wax droplets are visible on the top surface of each plate; a desk fan is positioned near one of the two plates; the clip begins only after any heat source (flame, glowing burner, heating element) has been removed or switched off.
level_4: All elements of score 3 are present AND the desk fan's blades are visibly turning (or dust/light debris near its outlet is visibly moving), showing it is actually running rather than just present; both plates stay in the same spot and fully inside the frame for the whole clip.
level_5: All elements of score 4 are present AND the fan's airflow is clearly aimed at only one of the two plates, with no visible disturbance (moving dust, rippling, etc.) near the other plate; the two plates keep the same facing toward the camera and the same surface finish throughout; nothing besides the fan's own motion enters or leaves the frame; neither plate nor its wax droplets are ever hidden behind another object.

Scientific and Causal Correctness rubric:
level_1: Both plates' wax droplets stay in exactly the same visual state (either both fully solid/rounded or both molten/flattened) for the whole clip with no transition on either plate, or the visible transition runs backward (solid, matte wax turning glossy and spreading out as the clip proceeds).
level_2: Only one plate's wax droplets visibly change from glossy/molten to matte/solid, but it is the still-air plate that finishes this change first or at the same time as the forced-air plate; or a change in the wax's appearance happens before the fan is shown turned on; or the wax's appearance changes for a non-thermal reason (e.g., an abrupt color shift or sudden disappearance unrelated to melting or solidifying).
level_3: The forced-air plate's wax droplets visibly stop being glossy and molten and settle into a duller, more rounded, static shape earlier in the clip than the still-air plate's wax droplets, which stay glossy/molten or keep gradually settling for a noticeably longer stretch of the recording; neither plate's wax reverses from solid back to glossy/molten.
level_4: All elements of score 3 are present AND once the forced-air plate's wax droplets reach their final duller, rounded shape they show no further visible change for the rest of the clip, while at that same point the still-air plate's wax droplets are still visibly glossy or actively settling; wax on neither plate drips off the plate edge or slides sideways.
level_5: All elements of score 4 are present AND the forced-air plate's glossy-to-matte transition clearly finishes before the still-air plate's does (or the still-air plate's wax droplets remain visibly glossy/unsettled through the final frame); at no shared moment in the clip do both plates' wax droplets look equally solidified, and the forced-air plate's wax is never the one still glossy while the still-air plate's has already gone matte.

Spatiotemporal Consistency rubric:
level_1: Either plate teleports to a new position between frames; a wax droplet vanishes from or appears on a plate between one frame and the next without a gradual shrinking/rounding motion; the desk fan appears or disappears abruptly; a plate's edges warp, shear, or bend between frames; the shot's lighting shifts abruptly with no visible cause (e.g., swinging from bright to dark, or the color cast suddenly changing).
level_2: One plate visibly rotates or slides on the surface between frames; a wax droplet's outline snaps to a new size or shape rather than changing gradually; the fan's blades stutter, freeze, or spin backward; the camera view pans, tilts, zooms, or refocuses mid-video.
level_3: Both plates stay fixed in the same position and orientation for the entire clip; each wax droplet's outline changes size or shape only gradually from one frame to the next, never jumping; the fan keeps spinning at a steady rate once it is turned on; no object blocks either plate or its wax droplets for more than a single frame.
level_4: All elements of score 3 are present AND the motion of the fan blades and any gradual change in a wax droplet's outline both proceed smoothly frame to frame, without stutter, strobing, or sudden changes in speed; neither plate nor any wax droplet appears to jump sideways or resize abruptly between adjacent frames.
level_5: All elements of score 4 are present AND no visible warping, smearing, ghosting, or doubled edges appear around either plate, the wax droplets, or the fan at any frame; the relative sizes and positions of the two plates, their wax droplets, and the fan stay proportionate and consistent throughout, with no frame showing an object briefly duplicated, distorted, or misplaced relative to its surroundings.