Domain: Natural Science — Environmental Science
Target concept: Cadmium Detection

Video generation prompt: Take 2 mL of cadmium-containing soil extract into a test tube, add 2 drops of dithizone solution, shake thoroughly, and observe the resulting solution.

Evaluation guide:
(i) Target concept: Visual confirmation of cadmium presence via dithizone-mediated colorimetric reaction.
Minimum mechanism: Dithizone must be added to cadmium-containing aqueous extract; mechanical agitation (shaking) must occur to enable complex formation and phase transfer; color development is contingent on both reagent presence and mixing-induced chemical equilibration: no spontaneous or pre-shake color.
(ii)Storyline: [Frame 0–2] Static shot: upright test tube containing soil extract (brownish-yellow translucent liquid) centered in view. [Frame 3–4] Dithizone bottle and dropper enter frame from right; dropper tip aligns over tube mouth. [Frame 5–6] Two discrete, spherical droplets detach and fall vertically into tube, contacting liquid surface. [Frame 7–10] Tube is grasped and shaken in smooth, rapid oscillatory motion (≥2 full cycles); liquid sloshes cohesively. [Frame 11–15] Motion stops; tube settles upright; entire liquid column transitions from colorless/yellow to uniform red or pink; hue appears only after motion cessation and persists. Perspective: Fixed frontal close-up, no camera movement, consistent lighting, full tube visible throughout.

Manual:
Experimental Procedure
1. Place 2 mL cadmium-containing soil extract into a clean test tube.
2. Add exactly 2 drops of dithizone solution using a dropper.
3. Cap and shake the test tube vigorously for 3–5 seconds.
4. Observe the color of the solution.
Observation of Experimental Phenomena
The solution turns uniformly red or pink after shaking — no color before addition, no color without shaking, no partial or streaky color.
Summary of Experimental Principles
Cadmium ions react with dithizone to form a stable, colored complex (Cd(dithizone)₂) that is soluble in organic solvents and exhibits characteristic red-pink chromophore absorption — used for qualitative detection in environmental soil testing.

Prompt Grounding rubric:
level_1: No test tube is shown; no soil extract is visible; there is no dithizone bottle or dropper; no shaking action occurs; none of the four required elements (test tube, soil extract, dithizone solution, dropper) appear anywhere in the video.
level_2: Only one of the four required elements appears (for example the test tube alone); the tube has no liquid inside, no dropper or dithizone bottle is shown, no drops are added, and no shaking takes place.
level_3: The test tube contains a liquid, a dithizone bottle and dropper are visible, drops are dispensed into the tube, and a shaking motion occurs; however the number of drops is not clearly two (only one drop is visible, or drops are added too fast to count), or the shaking looks perfunctory (a brief hand movement without visible tube motion).
level_4: All four elements are present and used correctly: the test tube holds the soil extract, the dithizone bottle and dropper appear, exactly two individually visible drops fall into the tube, and a clear shaking action follows; the only shortcoming is minor, such as the tube not being held fully upright while shaking, or the dropper tip briefly moving out of view between drops.
level_5: The test tube with soil extract is shown first; the dithizone bottle and dropper appear together; exactly two separate, visible drops fall into the tube and land on the liquid; a vigorous shaking motion is clearly performed for at least one full back-and-forth cycle; the tube returns to an upright, centered position afterward; every object and action matches the prompt's description of quantities and steps.

Scientific and Causal Correctness rubric:
level_1: There is no causal connection between the actions and the outcome: a red or pink color appears before the drops are even added, or the color appears without any shaking, or the resulting color is blue, green, or yellow, none of which match a cadmium-dithizone complex; or the color changes even though no soil extract was in the tube.
level_2: Dithizone is added and the tube is shaken, but the resulting color is wrong for this reaction (purple, brown, or green instead of red or pink); or a color appears at the surface only without mixing through the liquid; or a red/pink tint appears before any shaking occurs; or a color appears briefly then fades right after shaking with no stable result.
level_3: Two drops of dithizone are added to the soil extract in the tube, the tube is shaken, and the liquid develops a red or pink tint afterward; but the color is uneven (the top half looks red while the bottom stays colorless), or only the spot where the drops landed shows color, or the container holds a liquid that clearly is not the cadmium-containing extract.
level_4: The soil extract is present, two dithizone drops are added, the tube is shaken, and a red or pink color develops across the whole liquid column; but the color is only weakly visible (pale rather than distinctly red-pink), or the color appears to start forming before the shaking is finished, or the liquid looks cloudy enough that the red/pink hue is hard to identify with confidence.
level_5: The cadmium-containing soil extract (a yellow-brown liquid typical of a real extract) is clearly visible before any drops are added; two dithizone drops contact the liquid; shaking finishes completely before any color appears; once shaking stops, the entire liquid column turns a uniform, clearly saturated red or pink, matching the known cadmium-dithizone complex color, with no other hue, gradient, or instability.

Spatiotemporal Consistency rubric:
level_1: The test tube abruptly changes position or orientation between shots as if it had been swapped out; the liquid level jumps rather than changing gradually; the dropper appears at the tube's mouth with no visible path from the bottle; the shaking motion looks jerky, with two or more visible frame skips or abrupt reversals that don't match natural hand movement; the lighting flickers or shadows appear and vanish in ways that don't make sense.
level_2: One object's motion looks physically wrong: the dropper seems to jump from the bottle to the tube without a visible travel path, or the liquid surface deforms in an impossible way such as appearing to split into layers mid-air; the shaking motion starts and stops instantly with no ramp-up or slow-down; the shadow on the tube appears to face a different way than it did a moment before, with no change in the light source.
level_3: The tube, bottle, and dropper all stay visually present and in a coherent arrangement throughout, with no object vanishing or breaking apart; the shaking motion looks like a smooth, natural arc rather than a mechanical toggle; however one small issue is noticeable, such as the tube tilting more than 90° off vertical (past horizontal) during shaking and not returning fully upright by the end, or a brief moment where the falling drop is partly hidden by the dropper tip, or a little shakiness in the shot that doesn't change which object is which.
level_4: The tube, bottle, and dropper keep consistent positions relative to each other; the drop's fall from the dropper tip to the liquid surface is fully visible and unbroken; the shaking motion is smooth and ends with the tube upright and still; the final view shows the tube centered and motionless; the only shortcoming is a brief moment where a hand partially blocks the base of the tube, clearly shorter than the shaking itself, or a faint reflection that coincides with the color appearing without hiding the hue.
level_5: The test tube stays centered in the shot the whole time; the dropper, bottle, and tube keep a consistent spatial arrangement; both drops fall along the same vertical path with no stray movement; the shaking follows one smooth, bounded back-and-forth motion and ends with the tube upright and still; there is no moment where any object is blocked from view, no lighting jump, no shadow discontinuity, and no warping; everything keeps a stable size, shape, and perspective across the whole clip.