Domain: Engineering — Materials Science & Engineering
Target concept: Water absorption: Wool > Natural cotton

Video generation prompt: A piece of natural cotton fabric and a piece of wool fabric of the same size are placed side by side, with two beakers containing equal volumes of distilled water; both fabric samples are immersed in the distilled water simultaneously for about 20 seconds and then lifted at the same time.

Evaluation guide:
(i) Target concept: Relative water absorption capacity between wool and cotton as determined by macroscopic post-immersion water retention.
Minimum mechanism: Wool's fiber structure (internal porosity and keratin matrix) must give it a genuinely higher liquid-water retention capacity than cotton once both are fully wetted; water must behave as a Newtonian fluid under gravity-driven drainage; fabric geometry and immersion depth must be equivalent, and the immersion must last long enough for water to penetrate wool's water-resistant outer cuticle, so that material property remains the sole variable.
(ii)Storyline: [Frame 0–2] Static setup: two identical beakers with distilled water centered in frame; cotton and wool fabrics placed side-by-side above beakers, fully visible, distinct textures apparent. [Frame 3–4] Synchronous downward motion: both fabrics enter water surface at identical vertical level, menisci rise uniformly. [Frame 5–6] Full submersion: both fabrics fully below water surface, no air pockets. [Frame 7–8] Synchronous upward motion: both fabrics exit water surface at identical vertical level, menisci fall uniformly. [Frame 9–10] Post-lift static: fabrics suspended at same height, wool shows persistent hanging water mass; cotton shows minimal/no hanging water. Perspective: fixed frontal orthographic view; full visibility of both fabrics, both beaker rims, and water surfaces at all stages.

Manual:
Experimental Procedure
1. Place one piece of natural cotton fabric and one piece of wool fabric side by side.
2. Position two beakers containing equal volumes of distilled water adjacent to fabrics.
3. Simultaneously immerse both fabrics fully into water for about 20 seconds.
4. Simultaneously lift both fabrics out of water.
Observation of Experimental Phenomena
Wool fabric retains significantly more visible hanging water (larger/cohesive droplets, slower drainage) than cotton fabric immediately after lift.
Summary of Experimental Principles
Wool has higher water absorption capacity than natural cotton due to hydrophilic amino acid groups in keratin and porous fiber structure.

Prompt Grounding rubric:
level_1: The cotton fabric or the wool fabric is missing; or one or both beakers of distilled water are missing; or the fabrics are not placed side by side before immersion; or the two fabrics are not immersed at the same time or not lifted out at the same time; or fewer than two fabric samples appear on screen.
level_2: Both fabrics and both beakers of distilled water are present and the fabrics start out side by side, but: the two fabrics enter the water at clearly different moments, or are lifted out at clearly different moments, or one fabric is fully submerged while the other only brushes the water's surface, or the two beakers are not shown together in the same shot.
level_3: Cotton fabric and wool fabric are both present and placed side by side above two beakers of distilled water; both fabrics are fully immersed into the water at the same visual moment and lifted back out at the same visual moment; the immersion and lift happen in one continuous shot without a cut.
level_4: Everything required at the 3-point level holds, and in addition: the cotton and wool fabrics stay visually distinguishable by texture throughout (no blur or obstruction hides which is which); the two beakers stay in the same spot relative to each other between immersion and lift; nothing else blocks the view of either fabric or beaker during the immersion/lift.
level_5: Everything required at the 4-point level holds, and in addition: both fabrics enter the water at the same height relative to the beaker rim and exit at the same height relative to the beaker rim; no motion blur, strobing, or dropped frame obscures the moment either fabric touches or leaves the water; the water surface in both beakers behaves normally during the lift, without unnatural splashing or distortion.

Scientific and Causal Correctness rubric:
level_1: No visible difference in how wet the two fabrics look after lifting; or the cotton fabric looks more soaked than the wool fabric; or the wool fabric looks dry while the cotton fabric looks wet; or both fabrics look equally wet/dry right after being lifted out.
level_2: Both the cotton and wool fabrics are visibly wet after being lifted, but there is no clear difference in how much water is dripping or hanging from them; or the cotton fabric shows bigger drops or a longer drip than the wool fabric; or the wool fabric looks only evenly damp while the cotton looks patchy in a way that doesn't support wool holding more water.
level_3: After being lifted out, the wool fabric visibly holds more water than the cotton fabric: the wool shows a continuous hanging mass of water or sheeting droplets, while the cotton shows little to no hanging water (at most a faint surface sheen or a few small isolated beads); this difference is clear and unambiguous.
level_4: Everything required at the 3-point level holds, and in addition: the wool fabric's hanging water persists across several frames after the lift while the cotton fabric's surface water recedes quickly (beading up and disappearing or draining away cleanly), with no frame where cotton appears wetter than wool.
level_5: Everything required at the 4-point level holds, and in addition: the wool fabric visibly sags or pools under the weight of the retained water, while the cotton fabric keeps roughly its original flat shape; no odd effect (splash-back, rebound droplets, or water appearing to wick the wrong direction) contradicts wool holding more water than cotton.

Spatiotemporal Consistency rubric:
level_1: A cut, jump, or freeze-frame breaks the shot between immersion and lift; or the cotton fabric, wool fabric, or either beaker jumps to a new position or orientation between the start of immersion and the end of the lift; or the screen suddenly gets brighter/darker or flashes; or a fabric tears or a beaker cracks or deforms with no cause.
level_2: No cut or scene break, but the fabric's movement looks jerky rather than smooth; or a highlight on a fabric's surface slides across it in a way no real light source would produce; or one fabric visibly stretches or bunches up unnaturally during the lift; or the water level in a beaker jumps suddenly with no motion that would explain it.
level_3: The whole sequence from immersion to lift plays as one continuous shot (or, if there is a cut, it reads as seamless with no visible gap); the cotton fabric, wool fabric, and both beakers keep stable positions and spacing relative to each other; the lighting stays the same throughout; neither fabric nor beaker shows any tearing, cracking, or warping.
level_4: Everything required at the 3-point level holds, and in addition: both fabrics move smoothly and plausibly (no floating, snapping into place, or sudden speed changes); the water's meniscus rises coherently as each fabric goes in and falls back coherently (without oscillating) as each fabric comes out; the relative sizes of the fabrics and beakers stay stable, with no parallax glitch.
level_5: Everything required at the 4-point level holds, and in addition: both fabrics are lowered into and lifted from the water at a visually similar, steady pace, with neither one lagging or jerking relative to the other; the water surface in both beakers behaves in a visually comparable way during the immersion and lift; the edge of each fabric stays consistently visible against its beaker rim, without flickering in and out at the boundary.