Domain: Natural Science — Chemistry
Target concept: The acrylic liquid gradually solidifies upon exposure to light, transforming from a flowable liquid into a solid polyacrylic acid gel with no significant volume shrinkage.

Video generation prompt: Add an aqueous acrylic acid monomer solution (containing dissolved photoinitiator) to a test tube, initiate polymerization with light irradiation, and record the changes in the system's state with irradiation time.

Evaluation guide:
(i) Target concept: Photoinduced sol-gel transition of an aqueous acrylic acid monomer solution via free-radical polymerization.
Minimum mechanism: Dissolved photoinitiator absorbs UV/visible light, generating radicals that add across acrylic acid double bonds, linking monomers into a crosslinked polyacrylic acid network; because the reacting monomer is a minority solute in a mostly-water solution, the small bond-length contraction from polymerization is distributed through the bulk liquid and produces only a hard-to-see volume change, sufficient to arrest gravitational flow while preserving optical clarity and adhesion to the tube wall.
(ii) Storyline: Phase 1 (t=0): Static shot, upright test tube, empty → monomer solution added → level meniscus established. Phase 2 (t>0): Light activates; no immediate change, then progressive resistance to meniscus deformation on tilt. Phase 3 (t=max): Tube tilted ~30°; gel maintains the original meniscus contour without sagging, sliding, or detachment, and any meniscus dip stays small. Perspective: Fixed frontal/slightly angled view, no camera motion, full tube always in frame; lighting ensures direct illumination of the liquid column and visibility of the meniscus contour and wall adhesion.

Manual:
Experimental Procedure
1. Place empty transparent test tube upright in fixed frame.
2. Add colorless aqueous acrylic acid monomer solution (containing dissolved photoinitiator) until ~1/3 full.
3. Illuminate liquid column continuously with visible/UV light source aligned coaxially.
Observation of Experimental Phenomena
- Initial state: liquid forms a flat, reflective meniscus; flows freely when tube is tilted.
- During irradiation: meniscus becomes resistant to tilt; liquid ceases flowing and holds shape.
- Final state: a cohesive, non-dripping, transparent-to-opalescent gel fills the tube cross-section and stays in contact with the tube wall, with at most a barely visible meniscus dip.
Summary of Experimental Principles
Dissolved acrylic acid monomer undergoes photoinitiated radical polymerization into a crosslinked polyacrylic acid gel. Because water — which does not itself react or shrink — makes up most of the solution volume, the modest bond-length contraction from polymerizing the dissolved monomer is diluted through the whole liquid column and does not produce a visually significant volume change.

Prompt Grounding rubric:
level_1: No test tube is shown; no acrylic acid monomer solution is visible in it; no light source appears; none of adding liquid, irradiating it, or showing a state change occurs.
level_2: A test tube appears but is empty or holds an obviously wrong substance (e.g., colored dye, plain water); a lamp or light source is visible but is not pointed at the tube; the monomer solution is never poured in and irradiation never visibly starts.
level_3: A test tube holds a clear, colorless liquid; the liquid is shown being added (e.g., poured or dispensed from a dropper); a light source is visibly aimed at the tube; the video shows a before-irradiation moment and a during-irradiation moment as separate, distinguishable stages.
level_4: The monomer solution is added to the test tube, the light is switched on and kept aimed at the same liquid column, and the liquid's appearance visibly progresses from pooled/flowing liquid toward a firmer, gel-like mass; the tube stays in the same fixed framing throughout; no unrelated objects or actions appear.
level_5: Every element of the prompt is shown clearly and only once: the added monomer solution is unmistakably a single clear liquid (no dye, no visible mixing motion, no stray bubbles); the light turns on right after the liquid is added and stays fixed on the same section of tube for the whole clip; there is no cut, zoom, or camera reposition; the entire sequence plays out in one continuous shot with the same framing from start to end.

Scientific and Causal Correctness rubric:
level_1: The liquid stays completely fluid the whole time: it still pours or flows when the tube is tilted; no gel or solid mass ever forms; or the liquid instead evaporates, separates into layers, or turns cloudy without ever becoming rigid.
level_2: The liquid thickens or turns hazy but still sags, drips, or flows under gravity when the tube is tilted; it never holds its own shape; or its color changes in a way unrelated to gelation (e.g., yellowing or darkening) instead of staying a clear-to-slightly-hazy gel.
level_3: The liquid turns into a single cohesive mass that keeps its shape and does not sag or pool when the tube is tilted; the gel surface stays smooth; the gel is not cracked and has not visibly pulled away from the tube wall into an obvious gap; its color/clarity stays close to the original liquid (clear to only slightly hazy, no strong yellow/brown tint).
level_4: The sequence follows the correct order: the liquid starts fully mobile and level; nothing visibly changes right when the light turns on; the liquid then gradually stops flowing when the tube is tilted; the final gel holds a stable shape without sagging or dripping; no bubbling, boiling, layering, or unrelated color shift appears anywhere in the clip.
level_5: The liquid starts level and clear; irradiation shows no boiling, no steam, and no sudden meniscus jump; the loss of flowability happens gradually and only in one direction (it never becomes flowable again partway through); the final gel keeps essentially the same clarity as the starting liquid, with the gel surface still touching the tube wall along its length and, at most, an almost imperceptible meniscus dip rather than a visible gap or crack.

Spatiotemporal Consistency rubric:
level_1: The test tube's position, size, or shape suddenly changes between shots (e.g., it is replaced by a visibly different tube); the liquid's level or appearance jumps to a different state with no transition; the light switches fully on or off instantly with no beam or glow ever visibly growing or fading; the camera angle or zoom jumps abruptly partway through.
level_2: The tube shakes or rotates for no visible reason; the liquid's level changes suddenly rather than gradually; the light beam's position on the tube shifts without any camera or object motion to explain it; the shadow cast by the tube swings to a different side even though nothing else in the shot moved.
level_3: The tube shows only slight, brief jitter in its position; the meniscus height changes only in small, gradual steps rather than sudden resets; the light beam mostly stays aimed at the same spot on the tube but its brightness flickers a little without a clear cause; shadows stay on the same side of the tube but their softness varies slightly from frame to frame.
level_4: The test tube stays in the same place in the frame the whole time; the liquid surface changes smoothly with no sudden jumps; the light beam stays aimed at the same section of the liquid throughout; the shadow the tube and light source cast keeps a consistent direction and length across the clip; nothing in the scene stretches, warps, or changes shape unexpectedly.
level_5: The tube shows no visible drift in its position from first frame to last; the liquid meniscus moves in a smooth, gradual way with no sudden snap to a new level; the light beam's brightness and edge softness stay the same throughout; the shadow's length and angle change only in ways consistent with the fixed tube and light positions; the whole clip plays back smoothly with no stutter or jump between frames.