Domain: Natural Science — Physics
Target concept: Pharaoh's Snake

Video generation prompt: Place a porcelain dish containing an appropriate amount of sand on the table. Pour alcohol to moisten the sand, then mix baking soda and sugar, and spread the mixture over the sand. Ignite the mixture of baking soda and sugar on the sand.

Evaluation guide:
(i) Target concept: Gas-driven carbon extrusion via concurrent decomposition and dehydration reactions.
Minimum mechanism: Alcohol must evaporate rapidly upon ignition to initiate localized high temperature; baking soda must thermally decompose to provide alkaline catalyst (Na₂CO₃) and gas (CO₂/H₂O); sugar must dehydrate *in situ* under catalytic heat to form volatile fragments and solid carbon scaffold; gas pressure must exceed structural cohesion to drive vertical expansion.
(ii)Storyline: Frame 0–1: Static setup. Porcelain dish with dry sand. Frame 2–3: Alcohol poured → sand darkens uniformly, surface glistens. Frame 4: Baking soda + sugar mixture (white granular) spread as thin layer over moist sand. Frame 5: Flame touches mixture surface → immediate localized ignition. Frame 6–8: Black carbon structure emerges from contact point, growing upward continuously with thin smoke rising synchronously. Frame 9: Growth halts; stable black coil remains, smoke dissipates. Perspective: Fixed overhead or 30° oblique frontal view; full dish always in frame; no occlusion of sand surface or growth zone.

Manual:
Experimental Procedure
1. Place porcelain dish on table.
2. Pour alcohol to moisten sand in dish.
3. Mix baking soda and sugar; spread evenly over moist sand.
4. Ignite mixture surface with flame.
Observation of Experimental Phenomena
A fragile, coiled, matte-black carbonaceous structure (Pharaoh"s Snake) grows upward from the ignited mixture, accompanied by thin gray-white smoke. No melting or secondary flaming occurs.
Summary of Experimental Principles
Decomposition of baking soda (NaHCO₃) releases CO₂ and H₂O vapor; sugar (C₁₂H₂₂O₁₁) undergoes dehydration catalyzed by hot Na₂CO₃ residue, forming porous carbon. Rapid gas evolution pushes carbon upward into snake-like shape.

Prompt Grounding rubric:
level_1: None of the posted_prompt's core elements appear together: no porcelain dish, no sand, no alcohol-moistened sand, no baking-soda-and-sugar mixture spread on the sand, and no flame ever contacting anything; the dish/sand/mixture/ignition sequence is essentially missing.
level_2: At least one core element shows up (the dish alone, or dry sand alone, or the dry baking-soda-sugar powder), but the sequence is broken: the sand is never visibly moistened, the mixture is never spread onto the sand, or a flame appears with no mixture present to ignite; steps play out of the prompt's order (e.g., ignition shown before the mixture is spread).
level_3: A porcelain dish holds a mound of sand that looks darkened and damp where alcohol was poured; a granular white-to-off-white mixture of baking soda and sugar sits spread over the moistened sand; a flame is brought into contact with the mixture's surface; the moistening, mixture-spreading, and ignition happen in that order, matching the posted_prompt.
level_4: Beyond level 3, the dish clearly reads as unglazed ceramic rather than glass or glossy porcelain; the sand fills the dish's central area without spilling to its edges; the damp patch fully underlies the mixture with no dry sand showing through beneath it; the mixture stays confined to the sand's surface without touching the dish's rim; and the flame is applied directly to the mixture rather than held above or beside it.
level_5: Beyond level 4, individual sand grains are visible under the lighting; the alcohol-dampened patch shows a soft gradient (darker toward its center, lighter toward its edges), consistent with the liquid soaking outward rather than one flat uniform tint; the baking-soda-sugar layer looks evenly blended with no visible clumps of either ingredient; and the flame touches the mixture immediately, without hovering or flickering over bare sand first.

Scientific and Causal Correctness rubric:
level_1: After the flame reaches the mixture, nothing chemically happens: no upward expansion, no smoke, no color change; the white mixture just sits there, and the flame either goes out immediately or never visibly interacts with it.
level_2: The flame triggers some visible change, but not the correct one: the mixture chars flat in place instead of pushing upward; or it expands into a smooth, solid lump rather than a coiled, porous black structure; or the black structure grows with no accompanying smoke; or the resulting product looks glossy/tarry rather than matte black.
level_3: Once ignited, the mixture pushes upward into a fragile, coiled, matte-black porous carbon structure (the 'Pharaoh's Snake') that keeps lengthening from the ignition point; thin gray-white smoke rises together with the growth; the growth stops once the structure reaches its final height; the black structure never melts, bubbles, or catches a secondary flame.
level_4: Beyond level 3, the black structure's surface shows a visibly porous, thread-like or branching texture rather than a smooth solid rod; the smoke stays thin and see-through, rising from the base of the structure rather than billowing outward; no new flame reignites the black mass after it forms; and no leftover white powder is visible beneath or beside the finished black structure.
level_5: Beyond level 4, the black structure holds together while it grows, with no piece collapsing or breaking off before growth ends; the smoke's intensity tracks the growth: starting at ignition, thickest during active lengthening, and fading once growth stops; the finished structure keeps a uniform matte-black finish with no shiny or tarry patches and no ashy white streaks; and no brown, red, or yellow discoloration appears anywhere along it.

Spatiotemporal Consistency rubric:
level_1: Severe spatiotemporal break: the dish jumps to a new position between frames; the sand mound vanishes and then reappears; the flame's position changes with no visible path connecting the two locations; the black structure appears already fully grown with no visible growth process; the light source's direction or brightness switches from one shot to the next with no transition; or the camera's viewpoint changes mid-sequence.
level_2: Moderate break: the dish stays put but the sand shifts position with no visible cause; the flame's brightness cuts in and out rather than flickering naturally; the black structure's height jumps at least twice instead of lengthening continuously; smoke appears in some frames and is missing from others in between; the shadow cast by the dish or the growing structure swings to a different direction even though the light hasn't moved; or background elements stretch or skew.
level_3: The dish keeps the same position and orientation throughout; the sand mound keeps its shape and place aside from the moistening and mixture-placement described in the prompt; the flame stays anchored at the ignition point on the mixture; the black structure lengthens continuously upward from that same point without skipping frames; the smoke rises steadily upward without sudden sideways jumps; and the shadows cast by the dish and the growing structure keep a steady direction and strength across the sequence.
level_4: Beyond level 3, the flame's flicker looks natural rather than freezing or strobing; the black structure's upward growth is smooth, without visible pauses or sudden speed-ups; the smoke rises in a gentle, layered stream rather than puffing or scattering erratically; and the dish, sand, and structure show no sudden shift in size, position, or camera angle from one frame to the next.
level_5: Beyond level 4, no frames are dropped or repeated in the sequence; the flame stays visibly anchored at the same spot on the mixture across the whole burn, with no perceptible drift; the black structure's growth rate looks steady to the eye, without sudden accelerations or slowdowns; the smoke's thickness builds and fades smoothly from when it starts to when it dissipates; and the framing shows no sudden zoom, focus shift, or perspective change during the sequence.