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

Video generation prompt: Place a transparent beaker on the table, put a small amount of red phosphorus in the crucible, insert the crucible into the bottom of the beaker and ignite it.

Evaluation guide:
(i) Target concept: Combustion of red phosphorus produces phosphorus pentoxide as an immediate, visible, opaque white fume under confinement in air.
Minimum mechanism: Red phosphorus must be in direct contact with atmospheric oxygen; ignition must supply activation energy; product must form as sublimed P4O10 vapor that condenses into colloidal solid particles, yielding macroscopically opaque, non-transparent, rising white fumes with no persistent flame.
(ii)Storyline: [Frame 1–2] Beaker placed on table → [Frame 3–4] Crucible inserted into beaker → [Frame 5–6] Red phosphorus placed inside crucible → [Frame 7] Flame applied directly to red phosphorus → [Frame 8] Flame ignites red phosphorus (visible luminous origin at phosphorus mass) → [Frame 9] White fumes emerge upward from phosphorus site → [Frame 10] Fumes disperse upward, obscuring crucible base and lower beaker interior; red phosphorus mass fully consumed. Perspective: Fixed frontal view, eye-level, no camera motion; all events occur within beaker interior and remain fully visible through transparent walls; no occlusion by hands or tools after ignition.

Manual:
Experimental Procedure
1. Place a transparent cylindrical beaker upright on a flat table surface.
2. Put a small amount of dark red granular red phosphorus into a ceramic crucible.
3. Insert the crucible fully into the beaker so it rests on the bottom.
4. Ignite the red phosphorus using a flame source applied directly to it.
Observation of Experimental Phenomena
- Red phosphorus ignites with a yellow-white flame.
- Dense, opaque white fumes (phosphorus pentoxide) generate immediately and rise upward, filling the lower interior of the beaker.
- The red phosphorus solid visibly diminishes and disappears completely.
- No flame persists after fume generation begins; only glowing embers may briefly remain.
Summary of Experimental Principles
Red phosphorus combusts in air to form phosphorus pentoxide (P4O10), a white solid that condenses as dense, opaque white fumes. This exothermic reaction requires direct ignition and proceeds rapidly in confined space, with fumes remaining suspended due to low convection in beaker.

Prompt Grounding rubric:
level_1: No transparent beaker appears; no crucible is visible; no red phosphorus is shown; no ignition action occurs; none of the required objects (beaker, crucible, red phosphorus) appear together at any point.
level_2: At least one of the three core objects appears, but the spatial setup does not match: the beaker is not resting on the table, the crucible is not inside the beaker, or the red phosphorus is not inside the crucible; no ignition action of any kind is shown.
level_3: The transparent beaker sits on the table, the crucible is inside the beaker, and dark red granular red phosphorus is visible inside the crucible; however, no flame, spark, or heat-induced glow ever appears near the phosphorus, so no ignition is depicted.
level_4: The beaker, crucible, and red phosphorus are arranged as in level 3, and a flame or spark is visibly applied near the phosphorus; however, the flame's source does not clearly originate from a tool making direct contact with the phosphorus itself: for example, a match is held outside the beaker, or the flame only touches the crucible rim rather than the phosphorus.
level_5: The beaker, crucible, and red phosphorus are arranged as in level 3, and a flame source (such as a lit match or heated wire) is shown making direct contact with the red phosphorus itself, with this contact happening only after the crucible and phosphorus are fully placed inside the beaker; the ignition tool never touches the crucible or beaker instead of the phosphorus.

Scientific and Causal Correctness rubric:
level_1: Red phosphorus is shown as a white, yellow, or orange powder or liquid rather than its actual dark red granular form; no smoke or fumes ever appear; no combustion phenomenon (glow, flame, or fume generation) occurs at any point.
level_2: Red phosphorus correctly appears as a dark red granular solid, but after ignition nothing changes: no glow, flame, or fume appears; or the combustion produces indicators that are scientifically wrong for this reaction, such as thick black sooty smoke, a pure blue or green flame with no yellow component, or colored (non-white) fumes.
level_3: Red phosphorus appears as a dark red solid inside the crucible; after ignition, a flame appears at its location and white fumes (dense, opaque, cloud-like) begin emerging from the phosphorus and start filling the lower interior of the beaker, but the fumes stay confined near the bottom rather than continuing to rise and disperse upward.
level_4: White fumes rise continuously upward from the red phosphorus and visibly spread through more of the beaker's interior; the red phosphorus visibly shrinks in quantity as fume generation continues; the flame itself dies down once dense fume generation is underway, consistent with the reaction shifting from open flame to fume-producing oxidation.
level_5: The red phosphorus is fully consumed, leaving no solid residue in the crucible by the end of the sequence; the white fumes come to occupy the lower-to-mid interior of the beaker, dense and opaque enough that the crucible base is no longer visible through them; the beaker and crucible show no discoloration beyond mild browning at the point of direct flame contact, and no black soot, colored fumes, or non-white smoke ever appear.

Spatiotemporal Consistency rubric:
level_1: The beaker's position on the table changes abruptly between two frames with no motion connecting them; the crucible appears inside the beaker in one frame and sitting outside it in the very next frame; a flame or fume appears in a frame where the previous frame showed no ignition action at all; the red phosphorus disappears from the crucible in one frame and reappears later without any placement being shown; the scene's overall brightness snaps abruptly from bright to dark (or the reverse) between consecutive frames with no light source shown changing; the crucible appears to float inside the beaker with no visible support, or the beaker's transparent wall flickers between transparent and opaque for no reason.
level_2: The crucible shifts to a different position inside the beaker between two frames with no motion shown connecting them; the flame casts no shadow at all, or its shadow points in a direction inconsistent with the rest of the scene's lighting; the white fumes are shown passing in front of the crucible but rendering behind the beaker's glass wall inconsistently, breaking the sense of depth.
level_3: The beaker stays in the same spot on the table throughout; the crucible stays fully inside the beaker for the whole sequence; the red phosphorus stays inside the crucible until the flame is first shown touching it; once flame and fumes appear, they originate from the same fixed spot in the crucible without jumping sideways; the phosphorus does not disappear and reappear at any point; shadows cast by the beaker and crucible stay on the same side throughout, consistent with one unmoving light source.
level_4: The flame's appearance has a brief, visible onset rather than appearing at full size in a single frame; the rising fumes follow a smooth, gently curving upward path rather than surging sideways or downward or jumping frames; the beaker's glass consistently shows the same reflection and slight distortion of objects behind it throughout the sequence, with no frame where this suddenly looks flat or different.
level_5: The flame's growth, the fumes' upward drift, and the red phosphorus's gradual disappearance all read as one continuous, physically coherent sequence with no frame that looks skipped or doubled; the beaker's transparency renders the crucible and background consistently: thin patches of fume let the crucible show through while thick fume fully hides it, and this thin/thick relationship changes smoothly rather than switching abruptly; the crucible's position relative to the table edge in the background stays consistent throughout, with no frame where it appears to jump in front of or behind background elements.