Domain: Natural Science — Chemistry
Target concept: Heated iron filings emit light in air but do not decompose.

Video generation prompt: Iron filings are heated in an open crucible using the flame of a laboratory burner, and then the flame is removed.

Evaluation guide:
(i) Target concept: Incandescence of elemental iron in ambient air without oxidation or phase change.
Minimum mechanism: Iron must reach ~500–800°C to emit visible red light via blackbody radiation; air must be present but insufficient to oxidize iron rapidly at this timescale; crucible must conduct heat but not itself glow significantly; thermal inertia allows red glow to persist briefly after heat source removal.
(ii)Storyline: [Frame 0–2] Crucible with loose black/gray iron filings at rest, no flame. [Frame 3–5] Bunsen flame contacts crucible base; filings remain static, no immediate glow. [Frame 6–7] Filings begin glowing uniformly red (not orange/yellow); crucible unchanged. [Frame 8] Flame fully removed; glow persists. [Frame 9–10] Glow dims gradually but remains red until near extinction; filings retain granular form and position. Perspective: Fixed frontal view, shallow depth, crucible centered, no occlusion, top of crucible fully visible (open), flame origin always traceable to burner nozzle.

Manual:
Experimental Procedure
1. Place iron filings in an open crucible (ceramic/porcelain or metal, as long as the crucible material does not itself glow when heated).
2. Heat the crucible from below using a laboratory Bunsen burner flame until filings glow red.
3. Remove the flame while keeping crucible stationary.
Observation of Experimental Phenomena
Iron filings glow red during heating and continue glowing red after flame removal; they remain solid, granular, and unchanged in color/shape; no smoke, sparks, melting, or decomposition occurs.
Summary of Experimental Principles
Heated iron filings emit light in air due to incandescence (thermal radiation), but do not decompose — their chemical identity and physical state remain intact.

Prompt Grounding rubric:
level_1: No crucible appears in the shot; no iron filings are visible; no flame from a lab burner ever touches the crucible; or the sequence never shows the flame being taken away afterward.
level_2: A crucible with iron filings inside is visible, but no burner flame ever appears; or a flame appears somewhere in frame but never actually touches the crucible; or the flame stays in contact with the crucible for the whole clip with no removal shown.
level_3: A crucible holding iron filings sits in frame; a burner flame is applied to the base or side of the crucible; the flame is then pulled away while the crucible stays in the shot; placement, heating, and flame removal all happen in that order.
level_4: Everything required for score 3 holds, and additionally the crucible's top stays open and unobstructed (no lid); the iron sits as loose filings rather than a solid clump or dust cloud; the flame is clearly a standard gas burner (visible barrel, adjustable air intake); the moment of flame removal is unambiguous: the flame either goes out or the burner is visibly pulled back while the crucible doesn't move.
level_5: Everything required for score 4 holds, and additionally the crucible is a standard lab crucible: porcelain/ceramic or metal are both acceptable, but whichever material is shown must itself stay unglowing and visually unchanged throughout (a thin metal crucible that starts glowing itself would fail this level); the iron filings look distinctly dark gray or black before any heating begins; the flame only touches the crucible during the heating phase, never before first contact or after removal; nothing else (tongs, gloves, labels) enters or dominates the frame.

Scientific and Causal Correctness rubric:
level_1: The iron filings visibly melt, flow, vaporize, or vanish; they turn red, orange, or yellow while the flame is still being applied but before any reasonable heating time has passed; or they show smoke, sparks, bubbling, rust-colored change, or any other sign of a chemical reaction rather than simple glowing.
level_2: The filings glow, but the color sequence is wrong (orange or white appearing before red); the glow looks identical whether the flame is on or already removed, with no build-up or fade; the glow appears the instant the flame touches the crucible with no delay; or the glow disappears the moment the flame is pulled away instead of lingering.
level_3: The filings start glowing only after the flame has been applied for a moment, the glow grows stronger while the flame stays on, and it keeps glowing red for some time after the flame is taken away; the glow stays red rather than shifting to orange, yellow, or white; nothing melts, changes shape, or shows signs of rusting, smoking, or residue.
level_4: Everything required for score 3 holds, and additionally the glow is confined to the filings themselves rather than spreading to the crucible walls or base; the glow gets brighter only while the flame is on and fades only after the flame leaves; the crucible itself never changes color or starts glowing; the filings keep their granular shape and spread throughout, without clumping together or shifting due to heat currents.
level_5: Everything required for score 4 holds, and additionally the crucible shows no glow of its own at any point, only the filings do; after the flame is removed, the glow visibly fades through at least three noticeably different brightness stages (bright red, dim red, then out) rather than switching off all at once; no glare or halo around the glow hides the true edges or texture of the filings.

Spatiotemporal Consistency rubric:
level_1: The crucible jumps to a new position or angle between moments; the iron filings vanish and then reappear; the flame appears in a new spot with no travel shown; the overall scene lighting flips or the shadow suddenly points a different way with nothing to explain it; the crucible looks cracked or bent in a way solid metal or ceramic wouldn't.
level_2: The crucible or filings look like they're wobbling, warping, or morphing slightly across moments; the flame flickers with an unnatural rhythm (strobing, freezing in place, pulsing on and off); a shadow cast by the flame or crucible disappears and comes back inconsistently; the lab bench or background behind the crucible looks like it's shearing or stretching.
level_3: The crucible stays fixed in the same spot throughout; the iron filings stay inside the crucible without spilling out or floating; the flame's base stays anchored at the burner's nozzle; shadows cast by the flame and crucible stay consistent with a single unmoving light source the whole time.
level_4: Everything required for score 3 holds, and additionally the flame grows and shrinks smoothly as it's adjusted rather than jumping in size; the crucible shows no shaking or vibration; the filings don't shift position during heating or after flame removal as if blown by convection; the overall brightness of the scene changes gradually rather than in sudden steps.
level_5: Everything required for score 4 holds, and additionally the whole clip plays without stutters, skipped frames, or repeated frames; the flame's outline stays sharp and steady rather than smearing or flickering unnaturally; the crucible's surface and the texture of the filings look the same from moment to moment, without shimmering or crawling.