Domain: Natural Science — Physics
Target concept: Food dye diffusing in warm water vs. food dye diffusing in cold water

Video generation prompt: Two identical transparent beakers are placed side by side on a table, the left beaker labeled 'WARM' and the right beaker labeled 'COLD'; the left beaker contains warm water and the right beaker contains cold water; a drop of blue food coloring is simultaneously added to the center of the water surface in each beaker.

Evaluation guide:
(i) Target concept: Temperature-dependent dye dispersal rate in liquid water.
Minimum mechanism: Dye must stay suspended and mixing within the liquid phase in both beakers (not evaporating, precipitating out, or reacting chemically); the water in both beakers must remain liquid throughout (no boiling, no freezing, no ice); the warm beaker's faster molecular motion and lower viscosity are expected to produce a more vigorous, plume-like convective spread than the cold beaker's slower, more compact spread. Such convective bulk motion driven by the temperature/density difference is part of the expected mechanism, not a violation of it.
(ii) Storyline: Frame 0–1: Two static beakers side by side on a tabletop, the left bearing a 'WARM' label and the right a 'COLD' label, both filled with still, colorless water. Frame 2: Two identical blue dye drops appear simultaneously at the centers of both water surfaces. Frame 3–8: Dye disperses radially outward; the WARM-labeled beaker shows a faster, irregular, plume-like spread; the COLD-labeled beaker shows a slower, more rounded and compact spread. Frame 9: The difference in spread extent is maximally visible: the WARM beaker's dye occupies a noticeably larger area with a diffuse edge, while the COLD beaker's dye remains smaller with a defined edge. Perspective: Fixed frontal view, eye-level, centered on the beaker pair; full beaker height, both labels, and the water surfaces are fully visible; no occlusion of either dye region; lighting is uniform and diffused so it does not mask the visible difference in spread.

Manual:
Experimental Procedure
1. Place two identical transparent cylindrical beakers side by side on a flat surface; affix a small label reading 'WARM' to the left beaker and 'COLD' to the right beaker.
2. Fill the left (WARM-labeled) beaker with warm water (not steaming), and the right (COLD-labeled) beaker with cold water (no condensation).
3. Simultaneously add one drop of blue food coloring to the center of the water surface in each beaker.
Observation of Experimental Phenomena
In the WARM-labeled beaker, the blue dye spreads rapidly outward in irregular, plume-like tendrils driven by faster molecular motion and small-scale convective currents, occupying a visibly larger area by the end of the video. In the COLD-labeled beaker, the dye spreads more slowly and evenly, remaining compact and centrally concentrated with a sharper boundary.
Summary of Experimental Principles
Dye disperses faster in warmer water because higher thermal energy increases molecular kinetic energy and lowers viscosity, which both speed random molecular motion and favor small-scale convective currents; together these accelerate the visible mixing of dye into water compared with the cooler, more viscous beaker, where spread stays slower and more orderly.

Prompt Grounding rubric:
level_1: The scene shows no two transparent beakers side by side, or only one beaker; no WARM/COLD labels are present on either beaker; no water is visible in the beakers; no blue food-coloring drop is added to either beaker.
level_2: Two transparent beakers side by side are visible and each contains water, but at least one required setup element is wrong or missing: the WARM/COLD labels are absent, illegible, or swapped from the left/right convention; blue dye is added to only one beaker; or one beaker differs in shape, size, or material (e.g., opaque, tinted, non-cylindrical) from the other.
level_3: Two identical transparent cylindrical beakers sit side by side, the left labeled WARM and the right labeled COLD, each filled with visibly still water; a drop of blue food coloring is added to each beaker; however, the two drops are added with a clearly noticeable time gap (one appears several frames before the other) rather than together.
level_4: All conditions of the 3-point level hold, and the two dye drops are added at essentially the same moment (same frame or immediately adjacent frames); beaker size, shape, color, label placement, and water level match between the two beakers; one minor non-core imperfection remains (e.g., a slightly crooked label, a faint reflection, or brief background clutter) that does not affect legibility of the labels or visibility of the beakers.
level_5: Two identical transparent cylindrical beakers are side by side with clearly legible WARM (left) and COLD (right) labels; both contain equal, calm water levels; one drop of blue food coloring lands at the center of each beaker's surface within the same frame; beaker dimensions, label style, and camera framing are identical between the two beakers; no extraneous objects, no missing or incorrect labels, and no deviation from the prompt's described setup.

Scientific and Causal Correctness rubric:
level_1: Dye dispersal looks identical in both beakers regardless of the WARM/COLD label, or the dye does not spread at all in either beaker, or the COLD-labeled beaker visibly disperses dye faster or wider than the WARM-labeled beaker.
level_2: A difference in dispersal rate between the two beakers is visible, but it is not attributable to temperature: the dye appears to move before the drop touches the water, the two drops are unequal in size or volume, or the visible difference is only in color intensity rather than in spread extent.
level_3: After both drops contact the water, the WARM-labeled beaker's dye visibly spreads to occupy a larger, more diffuse area than the COLD-labeled beaker's dye, which stays smaller and more compact; the WARM beaker's spread also looks more irregular and plume-like while the COLD beaker's stays rounder, consistent with faster molecular motion and convective mixing at higher temperature.
level_4: All conditions of the 3-point level hold, and the extent gap between the two beakers grows steadily over the sequence and never reverses so the COLD beaker briefly looks bigger; the dye's hue stays blue throughout in both beakers with no fading to a different color; only a minor non-core imperfection remains, such as a slightly uneven dye edge in one frame.
level_5: The WARM-labeled beaker's dye area is clearly and continuously larger than the COLD-labeled beaker's from the moment of contact through the final frame, with the size gap widening monotonically; the WARM beaker's dispersal shows visible plume-like branching while the COLD beaker's stays smoothly rounded; dye color, opacity, and spread rate are physically consistent with temperature-driven differences in molecular motion and convective mixing, with no reversal, color distortion, or unexplained pause in either beaker.

Spatiotemporal Consistency rubric:
level_1: A beaker's position or size changes abruptly between one frame and the next, as if it jumped to a new spot, without any continuous motion connecting the two states; the water surface disappears and reappears; a dye drop appears in the beaker with no visible drop or motion leading up to it; or the camera view suddenly cuts to a different angle or zoom mid-sequence.
level_2: A beaker or its label visibly slides, resizes, or reorients between phases of the sequence by more than its own width or height, with no corresponding camera motion; the water surface flickers on and off for more than one frame; the dye drop's fall is choppy, freezing in place for three or more frames and then jumping to the next position instead of moving continuously.
level_3: Both beakers, their WARM/COLD labels, and the water surfaces stay in the same position and size throughout the sequence; the dye drop descends and touches the water with a continuous, visible motion path; no beaker, label, or water surface appears, disappears, or jumps unexpectedly.
level_4: All conditions of the 3-point level hold, and the dye's spreading motion after contact is smooth and gradual frame to frame with no sudden freeze-then-jump in the spreading pattern; the lighting on both beakers stays even and matched throughout, without one beaker suddenly appearing brighter or darker than the other; only one small non-core flaw remains, such as a brief, faint highlight shift on the glass that does not affect visibility of the beakers or labels.
level_5: Across the entire sequence, both beakers, their labels, the water surfaces, and the spreading dye stay geometrically consistent frame to frame with smooth, continuous motion and no visible freeze, stutter, or sudden repositioning; the camera viewpoint never shifts; lighting and reflections on the glass evolve gradually and match between the two beakers throughout, with no abrupt brightness or shadow change on either beaker.