Domain: Natural Science — Chemistry
Target concept: Combustion of White Phosphorus

Video generation prompt: Place a transparent beaker on the table, put a small amount of white phosphorus into the crucible, insert the crucible to the bottom of the beaker, and expose the phosphorus to the air inside the beaker.

Evaluation guide:
(i) Target concept: White phosphorus has an unusually low autoignition temperature (commonly cited around 30–40°C). Once its surface is exposed to atmospheric oxygen inside the beaker, slow oxidation begins immediately and is itself exothermic, gradually raising the phosphorus's own temperature until it reaches this threshold and bursts into flame, with no external flame, spark, or heated wire ever touching it.
Minimum mechanism: White phosphorus must sit in the open crucible with its surface exposed to air; no external ignition tool of any kind may contact the phosphorus at any point in the sequence; after an interval of exposure, a flame must originate directly from the phosphorus surface on its own; combustion must produce dense white P₄O₁₀ smoke rather than clear vapor or ash.
(ii) Storyline: Frame 1–2: Static wide shot of the empty transparent beaker on the table. Frame 3–4: The crucible enters frame and settles at the beaker's bottom. Frame 5–6: White phosphorus (a waxy, opaque white solid) is placed inside the open crucible, its surface exposed to air. Frame 7–8: The phosphorus sits inertly for a moment with no tool of any kind near it. Frame 9: A flame spontaneously appears at the phosphorus surface with nothing having touched it, and white smoke begins rising. Frame 10: The flame subsides as the phosphorus is consumed, leaving no residue. Perspective: fixed frontal mid-shot, no camera movement; the beaker's interior stays fully visible throughout, with the crucible and phosphorus never hidden by the beaker wall, a hand, or any tool.

Manual:
Experimental Procedure
1. Place a transparent beaker upright on a flat table surface.
2. Put a small amount of white phosphorus into a crucible.
3. Insert the crucible fully into the beaker so it rests at the bottom, leaving the phosphorus's top surface openly exposed to air.
4. Do not apply any external flame, spark, or heat source — simply leave the white phosphorus exposed to the air inside the beaker.
Observation of Experimental Phenomena
- After a short period of air exposure, a bright yellow-white flame spontaneously appears at the white phosphorus, with no match or spark ever having touched it.
- Dense white smoke rises continuously from the flame zone.
- White phosphorus visibly diminishes and disappears completely during combustion.
Summary of Experimental Principles
White phosphorus has an unusually low autoignition temperature (commonly cited near 30–40°C). Exposure to atmospheric oxygen causes slow surface oxidation that is itself exothermic, gradually heating the phosphorus until it spontaneously ignites without any external flame. Combustion produces phosphorus pentoxide (P4O10) as dense white smoke and releases intense light and heat via rapid exothermic oxidation.

Prompt Grounding rubric:
level_1: No transparent beaker is shown; no crucible is visible; no white phosphorus material appears; none of the three objects (beaker, crucible, white phosphorus) appear together in a correct configuration.
level_2: At least one of the three core objects appears, but is misidentified (e.g., an opaque container instead of a transparent beaker; a spoon instead of a crucible; yellow or clear wax instead of white phosphorus's characteristic waxy opaque-white appearance); the crucible is not shown placed inside the beaker, or the sequence of placement is reversed.
level_3: All three core objects are present and correctly identified: transparent beaker on the table, small crucible resting inside it, and white phosphorus (a waxy, matte white solid) sitting inside the crucible with its surface openly exposed to air (no lid or covering); no object is missing or substituted.
level_4: The beaker remains stationary on the table throughout; the crucible stays fully within the beaker's interior with no part protruding above the rim; the white phosphorus remains inside the crucible and its top surface stays open to the air (not submerged, covered, or removed) for the entire sequence; no match, spark, wire, or other ignition tool ever enters the frame or touches the phosphorus.
level_5: The beaker is unmistakably transparent, with no haze or reflection masking the interior; the crucible and phosphorus remain fully visible inside it at all times, never occluded by the beaker wall, a hand, or any tool; the white phosphorus keeps its waxy matte-white appearance right up until it begins to burn; from placement through any change in the phosphorus's state, no external object other than the beaker, crucible, and phosphorus ever enters the frame.

Scientific and Causal Correctness rubric:
level_1: No combustion phenomenon occurs; the white phosphorus sits inert with no light emission, smoke, or visible change; or any change shown contradicts combustion (e.g., melting without any flame, blackening, or vaporizing without a glow).
level_2: A luminous phenomenon occurs but is inconsistent with white-phosphorus combustion: the flame color is wrong (e.g., blue or green rather than bright yellow-white); the phosphorus disappears instantly with no visible smoke or residue; or the flame appears at the exact instant a tool or hand touches the phosphorus, implying it needed external ignition rather than igniting on its own.
level_3: A bright yellow-white flame appears at the phosphorus's location with no match, spark, or heated tool visible anywhere in the frame at the moment ignition begins; the phosphorus visibly diminishes in quantity; white smoke emerges from the flame zone; the flame persists for a clearly observable stretch of the sequence, not a single flicker.
level_4: The flame originates only from the phosphorus surface itself (not from the crucible metal or beaker base) and appears with no external tool or flame ever having touched the phosphorus beforehand; the smoke is dense, white, and rises upward from the flame zone; the phosphorus is fully consumed with no solid fragments left in the crucible; no condensation or charring appears on the beaker or crucible from the reaction.
level_5: The flame stays confined to the phosphorus mass itself and never spreads to the crucible walls or beaker interior; the smoke remains continuously white and voluminous, without gray, brown, or yellow tints; the flame dies out on its own once the phosphorus is fully consumed, with no lingering ember; at no point does any external heat source, spark, or flame contact the phosphorus prior to its self-ignition.

Spatiotemporal Consistency rubric:
level_1: The beaker's position or orientation on the table changes abruptly between frames with no motion shown connecting them; the crucible appears inside the beaker in one frame and outside it in the next; a flame appears in a frame where the immediately preceding frame showed no exposure period at all; the white phosphorus disappears from the crucible and then reappears later in the sequence.
level_2: The shadow cast by the crucible on the table suddenly appears on the opposite side between two consecutive frames, even though neither the light source nor the camera has moved; the crucible is partly hidden behind the beaker's glass wall in one frame and then fully visible in the next with no camera or object motion to explain the change; the overall lighting in the shot swings between bright and dark with no additional flame, spark, or light source appearing to explain the change; a flame switches on and off more than twice within the sequence in a way that reads as flickering rather than a single, genuine extinguishing.
level_3: The beaker stays in the same spot on the table for the entire sequence; the crucible remains inside the beaker throughout; the white phosphorus stays inside the crucible, visibly exposed to air, for a clearly observable stretch of frames before any flame appears: the flame does not erupt in the very first frame the phosphorus is shown; once ignited, the flame burns continuously until it goes out, without vanishing and reappearing; the shadow cast by the beaker and crucible falls on the same side throughout, consistent with one unmoving light source.
level_4: The flame's emergence is gradual rather than instant: it starts small at the phosphorus surface and grows, rather than appearing at full size in a single frame; the rising smoke follows a smooth, gently curving upward path with no sudden direction reversals or frame-skipping jumps; the beaker and crucible keep the same relative position to the table and to each other throughout the whole sequence, with no perspective jump between frames.
level_5: The flame's growth, the smoke's upward drift, and the phosphorus's gradual consumption all read as one continuous, unbroken motion from first appearance to final extinguishing, with no frame appearing to skip ahead of or double back on the one before it; the beaker's glass wall keeps a consistent, non-flickering transparency throughout; the crucible's edges and the table's edge in the background keep a consistent depth relationship, with the crucible never appearing to shift in front of or behind background elements inconsistently.