Domain: Natural Science — Chemistry
Target concept: The liquid monomer gradually becomes viscous, with a continuous decrease in fluidity, eventually forming a transparent polymeric gel, and the stirring resistance increases significantly.

Video generation prompt: Add styrene monomer and initiator into a transparent reactor, maintain constant temperature with continuous stirring, and dynamically record the changes in the liquid state.

Evaluation guide:
(i) Target concept: Free-radical polymerization-induced viscosity transition from Newtonian liquid to viscoelastic gel.
Minimum mechanism: Initiator must thermally decompose to generate radicals; monomer must be capable of chain propagation; absence of chain transfer/termination errors must allow progressive entanglement → continuous viscosity rise → percolation threshold → gel point.
(ii)Storyline: Frame 1–2: Empty transparent reactor in fixed frontal view. Frame 3–4: Styrene monomer poured in (clear, mobile liquid fills bottom). Frame 5–6: Initiator added (same vessel, no phase separation). Frame 7–9: Stirring begins → surface deformation deepens → meniscus flattens → rotation visibly dampens. Frame 10: Stirring stops → liquid does not flow; retains stirrer imprint → transparent gel confirmed. All events occur in single fixed-viewpoint shot; reactor interior fully visible at all times; no cuts, no zoom, no occlusion.

Manual:
Experimental Procedure
1. Place transparent reactor on platform.
2. Add colorless styrene monomer into reactor.
3. Add initiator (e.g., benzoyl peroxide) into reactor.
4. Start continuous stirring at constant speed.
5. Maintain constant temperature (no visible heater shown, but implied by stable setup).
Observation of Experimental Phenomena
- Liquid starts as free-flowing and level.
- Surface meniscus gradually flattens; stirrer rotation visibly slows or deforms liquid deeper.
- Liquid loses ability to flow freely: no dripping, no leveling after stirrer stops.
- Final state is cohesive, transparent, non-brittle gel that holds stirrer indentation.
Summary of Experimental Principles
Styrene monomer undergoes free-radical polymerization initiated by thermal decomposition of initiator; chain growth increases molecular weight, reducing mobility and increasing viscosity until crosslinked network forms transparent gel.

Prompt Grounding rubric:
level_1: No reactor visible; no styrene monomer or initiator shown; no stirring motion; no temperature control indication; none of the three required actions (addition, stirring, recording state change) present.
level_2: Reactor is present and transparent, but either styrene monomer or initiator is missing; stirring motion is absent or not continuous; no visual indication of state change progression (e.g., all frames show identical liquid appearance); at least one required action is partially depicted but others are fully missing.
level_3: Transparent reactor is present; both styrene monomer and initiator are visibly added into it (two distinct addition events or simultaneous co-addition); continuous stirring motion is clearly visible throughout; dynamic recording intent is implied by stable fixed viewpoint and unbroken framing; all three core actions (add, stir, record state evolution) are present in correct sequence.
level_4: All conditions for score 3 are satisfied, AND the reactor remains in the same spatial position and orientation across all frames; no object enters/exits frame mid-sequence; no substitution of container (e.g., beaker instead of reactor); no mislabeling or textual overlay contradicting posted_prompt (e.g., no “water” label); stirring rod remains fully visible and attached to stirrer mechanism without disconnection or flickering.
level_5: All conditions for score 4 are satisfied, AND the addition of styrene monomer and initiator occurs as two temporally separated, visually distinguishable events (e.g., two distinct pours or drops with clear onset/offset), followed immediately by onset of stirring, followed by unbroken observation of evolving state: no frame duplication, no jump cut, no temporal reordering, no occlusion of reactor interior during any phase.

Scientific and Causal Correctness rubric:
level_1: Liquid remains fully fluid and low-viscosity throughout; no increase in resistance to stirring; no viscosity change observable; no gel formation; no transparency change; no phenomenon matching the knowledge point.
level_2: Liquid shows minor surface texture shift (e.g., slight shimmer) but no discernible thickening; stirring motion unchanged in speed/amplitude; no visible resistance increase; no transition from liquid to gel-like state; no continuous decrease in fluidity evident.
level_3: Liquid visibly transitions from free-flowing to increasingly viscous: surface meniscus flattens, stirrer drag causes visible deformation of liquid surface or slower rotation response; transparency remains unchanged; final state shows cohesive, non-dripping, gel-like consistency (no pooling, no splashing, no separation); all phenomena align with the knowledge point “liquid monomer gradually becomes viscous… forming transparent polymeric gel”.
level_4: All conditions for score 3 are satisfied, AND the viscosity increase is continuous (no abrupt jumps, e.g., no sudden “solid snap” or discontinuous jump from liquid to rigid gel); stirring resistance increases progressively (stirrer rotation visibly slows or deforms liquid more deeply over time); no phase separation, cloudiness, or color change occurs; transparency remains fully intact throughout.
level_5: All conditions for score 4 are satisfied, AND the final gel state exhibits zero flow under gravity (e.g., no sagging, no edge rounding, no leveling when stirring stops); stirrer remains partially embedded or leaves persistent deformation upon cessation; no rebound or relaxation after stirring ends; all state changes occur *only* during stirring: no pre-gel solidification or post-stirring liquefaction.

Spatiotemporal Consistency rubric:
level_1: Reactor teleports between frames; stirrer disappears/reappears; lighting changes abruptly (e.g., frame-to-frame brightness inversion); liquid surface flickers discontinuously; structural integrity breaks (e.g., reactor wall bends unrealistically).
level_2: Minor spatial inconsistency: stirrer tip occasionally clips through reactor wall; one frame shows reactor tilted while others show upright; intermittent shadow discontinuity on stirrer shaft; liquid surface reflection inconsistently aligned with light source direction.
level_3: Reactor remains fixed in frame with consistent perspective; stirrer rotates smoothly around a single central axis without wobble or drift; liquid surface deforms continuously and plausibly under stirrer motion; lighting and shadows remain stable in direction and intensity; no object vanishes or reappears without cause.
level_4: All conditions for score 3 are satisfied, AND stirrer motion is mechanically consistent (e.g., no rotation without torque input; no inertial overshoot when stopping); liquid surface deformation propagates radially and decays naturally; no interpenetration between stirrer and liquid (e.g., stirrer never passes through liquid volume without displacement); no unnatural stretching or tearing of liquid surface.
level_5: All conditions for score 4 are satisfied, AND temporal pacing matches causal expectation: deformation appears *after* stirrer contact, thickening manifests *only after* sustained stirring, final gel holds shape *immediately upon stirring cessation*; no lag, anticipation, or desynchronization between action and physical response.