Domain: Natural Science — Chemistry
Target concept: Add a small amount of potassium permanganate crystals to distilled water, stir, and confirm that the solution immediately turns purple-red, with a uniform color and no layering phenomenon.

Video generation prompt: Place distilled water into a transparent beaker, add a small amount of potassium permanganate crystals, and gently stir with a glass rod. Pay close attention to the proper use of laboratory equipment, the correct sequence of operations, and the dissolution process.

Evaluation guide:
(i) Target concept: Visual confirmation of solute dissolution kinetics and ion-driven color formation in aqueous solution.
Minimum mechanism: Crystals must make physical contact with water to initiate dissolution; MnO₄⁻ ions must disperse via fluid motion (stirring) to achieve homogeneity; purple-red hue arises exclusively from solvated permanganate ions, not from suspended particles or impurities.
(ii)Storyline: Frame 0–2: Static shot of transparent beaker filled with colorless liquid (distilled water); Frame 3–4: Crystals descend vertically into water, contacting surface → immediate localized purple halo forms at impact site; Frame 5–7: Glass rod enters, stirs gently → purple region expands radially, forming transient diffusion plume; Frame 8–10: Stirring ceases → plume fully dissipates, leaving uniform purple-red liquid filling entire beaker volume; viewpoint remains fixed, front-lit, perpendicular to beaker face; all objects remain fully visible and unoccluded throughout.

Manual:
Experimental Procedure
1. Place distilled water into a transparent beaker.
2. Add a small amount of potassium permanganate crystals to the water.
3. Gently stir with a glass rod until crystals fully dissolve and solution becomes uniform.
Observation of Experimental Phenomena
Solution immediately turns purple-red upon crystal contact; color spreads radially during stirring; final solution is homogeneous, transparent, and uniformly purple-red with no layering or undissolved solids.
Summary of Experimental Principles
Potassium permanganate is highly soluble in water; its MnO₄⁻ ions impart intense purple-red color; dissolution is rapid and mildly endothermic (the solution cools slightly as the crystals dissolve), yielding a stable, colloidal-free aqueous solution.

Prompt Grounding rubric:
level_1: No transparent beaker, no distilled water, no potassium permanganate crystals, and no glass rod ever appear together in frame; none of the required lab items for this demonstration are shown.
level_2: Only some of the required items appear (e.g., the beaker and water but no crystals, or crystals shown without any prior beaker-and-water shot), and the actions happen out of order: for instance, the crystals appear already inside the liquid before any beaker-and-water shot, or the rod stirs before any crystals have been added.
level_3: The transparent beaker with distilled water, the potassium permanganate crystals, and the glass rod are all shown; the crystals are added into the beaker after the water is already present, but the rod is never inserted to stir, or stirring is shown only before the crystals have even touched the water.
level_4: The beaker with distilled water is shown first, the crystals are then dropped into the beaker, and the glass rod is inserted afterward and moved through the liquid in a stirring motion; the same single beaker and single rod are used throughout with no extra containers or tools entering frame.
level_5: Everything in score 4 holds AND the crystals are added as a small discrete cluster (not already mixed in before the shot begins); the rod performs at least two clearly visible stirring rotations while submerged in the liquid; and the beaker, water, crystals, and rod are the only lab items visible in every frame, with no jump cut that skips over the moment of crystal addition or the stirring action itself.

Scientific and Causal Correctness rubric:
level_1: The liquid in the beaker ends up colorless, blue, green, yellow, or cloudy instead of purple-red; crystals are still clearly visible as undissolved solid at the end; the liquid shows layers or settled sediment; or no color change happens at all once stirring starts.
level_2: Some color change happens but it is the wrong hue (e.g., plain pink or magenta without a red-leaning purple), the final color is streaked or patchy rather than even, distinct solid crystal particles are still visible at the end, or there is no visible spreading of color during stirring at all.
level_3: The final liquid is purple-red and looks mostly even, but a faint lighter patch remains near the top or bottom; the crystals are gone by the end, yet the color seems to appear everywhere at once rather than spreading outward from where the crystals landed; there is no layering, but the color's depth differs slightly between the top, middle, and bottom of the beaker.
level_4: The final liquid is evenly purple-red throughout the whole beaker with no region lighter or darker than another; no crystals remain visible; there is no layering or settling; the color starts right where the crystals first touch the water and keeps deepening as stirring continues; a spreading purple trail is visible fanning out from the crystals during the first few stirs and fully blends into the liquid before the end.
level_5: The final liquid is evenly purple-red with the same hue, depth of color, and clarity in every part of the beaker: top, middle, bottom, and near the glass walls; no trailing streak of color is left at the end; the color's spread is visible step by step: a halo forms right where the crystals land, then the first stir sends color spreading outward, then further stirring blends it into one uniform liquid; by the end there is no leftover solid, no visible boundary line in the liquid, and no cloudy or hazy patch anywhere.

Spatiotemporal Consistency rubric:
level_1: The beaker, the crystals, or the glass rod appears or disappears from one frame to the next with no motion causing it (e.g., the beaker is suddenly on screen with no one having placed it, or the crystals appear already inside the liquid with no drop-in seen); the room brightness snaps from light to dark within a single frame; or the view suddenly zooms, crops, or rotates with no camera motion shown.
level_2: One clear break occurs: the beaker's shape or size changes partway through the shot, the liquid level rises on its own without anything being poured in, the crystals disappear without visibly dissolving, the glass rod appears to pass straight through the beaker wall, or the shadow cast by the beaker swings to a different side even though no light or camera has moved.
level_3: Small, isolated flaws are visible but nothing structural breaks: for example, a brief flicker or dropped frame while stirring, a slight shift in the beaker's position during stirring, or the rod briefly blocking the view of the crystals right as they first touch the water; aside from that one flaw, the beaker never changes shape or loses its rim, and the room lighting stays the same brightness and color throughout.
level_4: None of the flaws in 1-score 3 occur: the beaker keeps the same size, shape, and position in frame from start to finish; the liquid surface stays level with no splashing or sudden rise; the glass rod keeps a consistent thickness and color as it moves; and the crystals only ever move by falling under gravity or being carried briefly by the stirring water, never floating or hovering on their own.
level_5: Everything in score 4 holds AND the beaker's reflections and tilt stay physically consistent frame to frame, the liquid's surface curve at the beaker wall looks physically natural rather than flat or oddly bulging, the rod's stirring motion speeds up and slows down the way a hand-driven motion would rather than moving at one constant robotic speed, and the crystals visibly slow down as they hit the liquid surface rather than passing through instantly.