Domain: Engineering — Geotechnical Engineering
Target concept: Comparison of Drainage Rates in Gravel, Sand, and Silt Layers

Video generation prompt: Three transparent columns are placed side by side, filled with gravel (left), sand (middle), and silt (right), respectively; the same volume of water is simultaneously poured into each column.

Evaluation guide:
(i) Target concept: Hydraulic conductivity is inversely related to particle size and directly governs saturated vertical drainage rate in homogeneous porous media.
Minimum mechanism: Water must move solely under gravity through interconnected voids; no external pressure, capillary rise dominance, or lateral flow; materials must be dry, cohesionless (gravel/sand) or low-cohesion (silt), and fully saturated during observation.
(ii)Storyline: Frame 0–1: Static shot showing three labeled, identically filled columns. Frame 2–3: Simultaneous initiation of water pouring into all three columns (liquid enters top edge at same instant). Frame 4–7: Continuous, side-by-side descent of water level in each column, with clear rank-order separation (gravel leading, silt lagging). Frame 8–10: Stable post-drainage state showing residual water height differences (highest in silt, lowest in gravel), with all columns fully visible and aligned. Perspective: Fixed frontal orthographic-like view, eye-level, no occlusion, full-column framing maintained throughout.

Manual:
Experimental Procedure
1. Place three identical transparent cylindrical columns side-by-side on a flat surface.
2. Fill left column with gravel, middle with sand, right with silt — all to same height.
3. Simultaneously pour equal volumes of clear water into each column from identical height.
Observation of Experimental Phenomena
Water drains downward fastest in gravel, moderately in sand, slowest in silt; water level descends continuously and at visibly different rates across columns.
Summary of Experimental Principles
Gravel has largest pore spaces → highest hydraulic conductivity → fastest drainage. Sand has intermediate pore size → moderate conductivity. Silt has smallest pores and higher cohesion → lowest conductivity → slowest drainage.

Prompt Grounding rubric:
level_1: Fewer than three transparent columns appear, or the columns are not arranged side by side, or there is no visible distinction among the three fill materials (gravel/sand/silt) by label or appearance, or water is never poured into any column.
level_2: Three side-by-side transparent columns appear, but at least one is mislabeled or visually indistinguishable from the others (e.g., all three look identical in texture and color), or water is poured into only one or two of the three columns, or the pouring happens one column at a time rather than together, or a column contains a clearly wrong fill (e.g., garden soil instead of sand, clay instead of silt).
level_3: Three transparent columns stand side by side: the left one holds coarse, irregular, visibly high-porosity gravel; the middle one holds uniform, medium-grained sand; the right one holds fine, homogeneous, low-porosity silt; the same volume of clear water is poured into all three in one synchronized pouring motion that starts and lasts about the same time in each.
level_4: Everything required at the 3-point level holds, and in addition: the gravel/sand/silt labels are legible next to their columns; the poured water is clearly colorless and transparent; the three columns match each other in height, diameter, and wall thickness; and no hand, tool, or on-screen text blocks the view of any column during pouring or drainage.
level_5: Everything required at the 4-point level holds, and in addition: pouring begins and ends at essentially the same moment in all three columns, with no visible lag between them; the initial water level reaches the same height in all three columns right after pouring stops; and no frame shows warping, reflection distortion, or a viewing-angle shift that throws the three columns out of alignment with each other.

Scientific and Causal Correctness rubric:
level_1: No drainage is visible in any column, or all three columns drain at the same visible speed, or the silt column drains fastest while the gravel column drains slowest (the reversed, physically wrong order), or the water vanishes from a column without any visible downward movement, or the water changes color during drainage.
level_2: Drainage is visible but its direction is unclear (e.g., it looks like it is moving sideways or upward rather than down), or only one or two of the three columns show any drainage, or the three columns start draining at noticeably different times with nothing in the video to explain why, or a column's drainage behavior contradicts its material (e.g., the silt column drains as fast as the gravel column, or shows channels of water rushing through it).
level_3: Downward drainage is visible in all three columns, and the rate clearly differs by column: the gravel column's water level drops fastest and most steadily, the sand column drains at a moderate, steady pace, and the silt column drains slowest, with its water level staying near the top noticeably longer than in the other two columns.
level_4: Everything required at the 3-point level holds, and in addition: none of the columns shows a sudden speed-up or full stop in drainage that isn't explained by its material; the water level in every column only ever falls, never rises or oscillates; and the silt column keeps a visibly damp band above its drained zone while the gravel and sand columns show comparatively little residual wetness above their drained portions.
level_5: Everything required at the 4-point level holds, and in addition: at every point where the three water levels can be compared, gravel's is lowest, sand's is in between, and silt's is highest; the order never crosses or reverses; none of the columns shows visible internal erosion, cloudiness, or grains being carried along with the draining water in a way inconsistent with its grain size; and the water surface in each column stays flat and level as it descends, without tilting, bulging upward, or an inverted (concave-up) meniscus.

Spatiotemporal Consistency rubric:
level_1: A column suddenly jumps to a different position between frames, or changes its size/orientation abruptly, or blinks out of frame for an instant and then reappears with no motion carrying it away or back, or the room's lighting swings between two very different states within one cut (e.g., bright to dark with no transition), or a column visibly warps, stretches, or shows fisheye-style distortion.
level_2: The three columns stay in fixed positions, but the pouring motion looks jerky or stroboscopic (water seems to enter in discrete stutters rather than a continuous stream), or the shadows cast by the columns swap to a different side of the frame without any matching change in the light source, or background elements flicker or tear, or the camera's viewpoint rotates or zooms during the sequence.
level_3: All three columns stay fully visible, stationary, and aligned side by side throughout; the apparent light source stays in the same position and brightness across the video, and the shadows the columns and water cast stay geometrically consistent with that light source; no column clips through another or tears visually; and the pouring motion looks smooth and physically ordinary (no water floating in place, no upward-falling water).
level_4: Everything required at the 3-point level holds, and in addition: the water surface stays in continuous contact with each column's inner wall as it descends (no visible gap, drip, or breaking film); no column shows water that appears to freeze mid-fall and then jump ahead; and the edges of all three columns stay sharp and undistorted throughout, without motion blur that hides the fill material's texture.
level_5: Everything required at the 4-point level holds, and in addition: motion throughout the video is smooth with no visible stutter or dropped frames; the transparency of all three columns stays optically consistent, without flickering refraction, color fringing, or glare that hides what's happening inside; and each column's water meniscus changes shape gradually as it descends, never appearing to snap or reshape instantly from one frame to the next.