Domain: Natural Science — Geology & Geophysics
Target concept: Settling process of mixed sand–silt–gravel after swaying in the clear water column

Video generation prompt: A transparent graduated cylinder containing clear water and a mixture of gravel, sand, and silt was sealed, shaken uniformly, and then placed upright to allow settling.

Evaluation guide:
(i) Target concept: Particle-size-dependent gravitational settling in quiescent fluid under gravity.
Minimum mechanism: Fluid must be static (no convection/currents), particles must differ in size/density, and fluid viscosity must dominate inertial forces, enabling Stokes regime behavior where settling rate ∝ particle diameter².
(ii)Storyline: [Frame 0–1] Cylinder upright with clear water and unmixed sediment at bottom; [Frame 2–3] Cylinder lifted and shaken with uniform back-and-forth motion (no rotation); [Frame 4] Cylinder placed firmly upright, no motion thereafter; [Frame 5–8] Gravel rapidly accumulates at base; [Frame 6–9] Sand deposits atop gravel with visible texture contrast; [Frame 7–10] Silt remains as diffuse, low-contrast haze above sand, progressively thinning but never fully clearing until final frame; all phases observed from fixed side-on viewpoint ensuring full vertical column visibility and unobstructed layer discrimination.

Manual:
Experimental Procedure
1. Fill transparent graduated cylinder with clear water.
2. Add mixture of gravel, sand, and silt.
3. Seal cylinder tightly.
4. Shake uniformly in vertical plane.
5. Place upright immediately and hold still.
Observation of Experimental Phenomena
Gravel settles first to bottom, sand settles second forming middle layer, silt remains suspended longest forming cloudy upper zone; water clarifies progressively from top downward.
Summary of Experimental Principles
Settling velocity depends on particle size, density, and fluid viscosity: larger/denser particles (gravel) settle fastest; finer particles (silt) remain suspended longest due to lower Reynolds number and higher drag-to-weight ratio.

Prompt Grounding rubric:
level_1: No transparent graduated cylinder appears; no clear water is shown; the gravel-sand-silt mixture is absent; no shaking motion occurs; the cylinder is never shown placed upright to settle - none of these required elements appear.
level_2: A transparent container appears but is not a graduated cylinder (e.g., a plain jar or beaker with no volume markings); water is present but looks tinted or cloudy rather than clear; only one of gravel, sand, or silt is visible, not all three; and the shake-then-place-upright sequence is only vaguely suggested rather than clearly shown as two distinct steps.
level_3: A transparent graduated cylinder with visible volume markings holds clear water and a visible mixture of gravel, sand, and silt before shaking; the cylinder is shaken with visible agitation, then set upright and left still; all required elements (cylinder, water, gravel, sand, silt, shake, upright rest) appear, but their order or camera angle is inconsistent - e.g., the shake is filmed from above while the settling is filmed from the side.
level_4: All required elements appear in one continuous, fixed-viewpoint scene in the correct order (mixture visible in clear water, then a uniform back-and-forth shake, then the cylinder set upright, then settling begins): coarse gray/brown gravel grains, finer tan/yellow sand grains, and a fine dull-gray silt fraction are each visibly distinguishable inside the graduated cylinder, and no sediment type is missing, swapped, or misrepresented.
level_5: Everything required for a 4 is met, and in addition: the cylinder stays perfectly upright and still for the entire settling phase with no visible wobble or drift; gravel, sand, and silt each keep a visually distinct appearance throughout (none blur together into a single mass); no hands, labels, or on-screen overlays ever enter the shot; and the camera keeps a strict side-on view showing the cylinder's full height so the whole settling column is visible from start to finish.

Scientific and Causal Correctness rubric:
level_1: No settling is shown at all - the gravel, sand, and silt appear either fully mixed and suspended or already fully settled in the very first frame, with no layering ever forming and no size-based separation visible.
level_2: Some particles sink, but gravel, sand, and silt all appear to settle at the same rate with no size-based separation; the water clears everywhere at once rather than gradually from top to bottom; there is no visible distinction in how quickly the three sediment types drop out of suspension.
level_3: Three settling stages can be told apart - gravel sinks first to form the bottom bed, sand settles next to form a middle layer, and silt stays suspended longest as a hazy layer above - but the layer boundaries are blurry or the silt haze is easy to mistake for glare or bubbles, and the water above never gets as clear as it was before shaking.
level_4: Gravel fully settles to the bottom before sand finishes settling, and sand fully settles before the silt haze meaningfully thins; the silt layer stays visibly cloudy and diffuse for an extended period, gradually clearing from the top down; by the end, three distinct zones are visible - a coarse gravel bed, a finer uniform sand layer above it, and a hazy silt suspension above that - with no layer order reversed and no sediment inexplicably floating.
level_5: Everything required for a 4 is met, and in addition: the silt haze thins evenly with no random clear patches opening up inside it; the settled gravel bed shows no grains kicking back up into suspension; the sand layer shows no visible mixing with the silt or gravel at its edges; and the water above the silt eventually becomes just as clear as the original water was before the mixture was added, showing that essentially all silt has settled out.

Spatiotemporal Consistency rubric:
level_1: The graduated cylinder's position or size jumps abruptly between shots rather than showing one continuous shake-then-settle take; the lighting abruptly shifts (e.g., bright to dark) between shots with no visible cause; the water surface distorts or tears unnaturally; the gravel/sand/silt mixture vanishes and reappears; the cylinder suddenly rotates or tilts with no visible cause; or the scene cuts or stutters so the shake-to-settle sequence is broken into disconnected clips.
level_2: The camera view shifts noticeably (e.g., from side-on to an angled view) partway through; the cylinder visibly wobbles or vibrates for an extended period after being set upright; the gravel, sand, or silt layers shift sideways with no corresponding cylinder movement; the water's top surface changes shape in a sudden, discontinuous way; or shadows cast on the cylinder noticeably flicker, disappear, or jump to a new direction.
level_3: The cylinder stays in the same place and orientation, the water surface stays level, and the gravel/sand/silt move only downward as they settle; there is no teleporting, no jump-cuts, and no sudden lighting change; overall motion looks smooth and physically reasonable, though the cylinder may still show a brief residual wobble right after being set upright, or the gravel-sand-silt interface may show a short, easily overlooked blur that clears up on its own without any visible break in the layer.
level_4: Everything required for a 3 is met, and in addition: the cylinder shows no visible wobble or vibration at all once set upright; the water surface stays completely flat and undisturbed; the boundaries between gravel, sand, and silt stay sharply visible and motionless once each layer has settled; and the camera framing and perspective stay consistent throughout, with no visible camera shake or drift.
level_5: Everything required for a 4 is met, and in addition: the gravel, sand, and silt grains keep a consistent apparent size and spacing throughout (none of them visibly grow, shrink, or morph); the cylinder's glass walls show no distortion of the background visible behind them; no motion blur ever obscures which layer a settling grain belongs to; and the overall brightness, color, and shadow direction on the cylinder stay the same from the first frame to the last.