Domain: Healthcare — Nutrition and Food Hygiene
Target concept: Heavy Metal Lead Testing

Video generation prompt: Place a small amount of water sample containing lead metal into a clean container, add the extraction solution, gently shake to mix, then immerse the dithizone paper for a few seconds. Remove the paper and compare it with the standard color chart to determine the presence of lead.

Evaluation guide:
(i) Target concept: Visual colorimetric detection of aqueous lead via dithizone complex formation.
Minimum mechanism: Lead ions must be present in water sample; extraction solution must provide acidic medium; dithizone paper must contain dithizone reagent; color development requires direct contact and time-limited immersion; comparison requires simultaneous visibility of developed paper and standardized chromatic reference.
(ii)Storyline: [Phase 1] Water sample is placed into clean container → [Phase 2] Extraction solution is dispensed into same container → [Phase 3] Container undergoes gentle oscillatory motion → [Phase 4] Dithizone paper is lowered vertically into solution and held → [Phase 5] Paper is lifted vertically out and held still → [Phase 6] Paper and standard color chart appear side-by-side in fixed frame; causal transitions require: solution addition precedes shaking, shaking precedes immersion, immersion precedes removal, removal precedes comparison; all phases must be visible from consistent frontal/oblique angle with no occlusion of key objects during critical actions.

Manual:
Experimental Procedure
1. Place water sample in clean container.
2. Add extraction solution.
3. Gently shake to mix.
4. Immerse dithizone paper for several seconds.
5. Remove paper and compare color to standard chart.
Observation of Experimental Phenomena
Dithizone paper turns red or orange after immersion; color intensity corresponds to lead concentration when matched against graded red-orange bands on standard chart.
Summary of Experimental Principles
Lead ions react with dithizone in acidic medium to form a red-orange chelate complex; color intensity is proportional to lead concentration — qualitative detection via visual colorimetric comparison.

Prompt Grounding rubric:
level_1: No water sample, no clean container, no extraction solution, no dithizone paper, and no standard color chart are present, and no hand or tool is shown performing any step of the procedure.
level_2: At least one correct object is present (e.g., a container or a paper), but three or more of the five core objects (water sample, clean container, extraction solution, dithizone paper, standard color chart) are missing, and the placement, mixing, immersion, removal, and comparison actions are absent or unidentifiable.
level_3: All five core objects appear at some point in the clip and are correctly typed: a water sample, a clean container, the extraction solution, the dithizone paper (not a plain filter paper or other substitute), and the standard color chart; the dithizone paper is shown having been immersed and then removed with a color already developed on it, and the color chart is shown for the comparison, regardless of the exact editing or shot ordering used to get there.
level_4: Everything required for a 3 holds, and in addition, during the final comparison the dithizone paper and the standard color chart are both fully within frame at the same time, close enough together that a viewer could compare them directly, with neither the hand, the container, nor any other prop blocking either one.
level_5: Everything required for a 4 holds, and in addition, the dithizone paper and color chart keep this directly-comparable arrangement for the entire comparison shot (the paper stays held next to the chart without drifting out of frame or being cropped at an edge), and both surfaces face the camera rather than being angled away from it.

Scientific and Causal Correctness rubric:
level_1: The dithizone paper shows no perceptible color change after immersion, staying its original pale color (white or pale yellow) before and after contact with the sample, and no comparison against the standard color chart is attempted or shown.
level_2: The dithizone paper changes color, but to an incorrect hue (e.g., blue, green, purple, or black) or the change happens before immersion even occurs; or the color chart shown displays hues outside the red-orange range, or lacks distinct graded bands.
level_3: The dithizone paper turns a red or orange color after immersion and removal; the standard color chart contains a series of red-to-orange graded bands; the paper is visually held up against the chart to judge lead presence, with no contradictory outcome such as a red paper being compared to a chart that only has blue bands.
level_4: Everything required for a 3 holds, and in addition, the dithizone paper's post-immersion color sits within the red-orange range and clearly corresponds to one specific graded band on the chart rather than reading as ambiguously between two bands or falling outside the charted range entirely.
level_5: Everything required for a 4 holds, and in addition, the dithizone paper's final color matches one specific band on the standard color chart in both hue and depth of color, so a viewer would confidently read off the same lead-concentration band from the paper as from the chart, with no ambiguity about which graded band it corresponds to.

Spatiotemporal Consistency rubric:
level_1: Severe spatiotemporal breaks: the container jumps to a different position or shape between shots, the dithizone paper appears in the liquid or in the hand with no visible motion bringing it there, the room's illumination jumps to a different brightness or color between shots with no visible transition, or the container appears to shatter and then reform intact.
level_2: Two or more major discontinuities occur: e.g., a hand enters the frame already holding the dithizone paper with no earlier shot showing it being picked up; the paper is shown dry and then instantly shown fully saturated with color, skipping the immersion motion; or the color chart appears in frame only after the paper is already colored, with no shot showing the chart being brought into view.
level_3: The procedure unfolds as one continuous shot or a logically ordered edit with no skipped steps: the water sample is placed in the container, the extraction solution is added, the container is gently rocked, the dithizone paper is lowered into the liquid, the paper is lifted back out, and finally the paper and chart are shown together; the container, paper, and chart are each visible through their relevant steps rather than popping in or out of frame, and the room's illumination keeps the same brightness and color cast from the first shot to the last.
level_4: Everything required for a 3 holds, and in addition, the motion is physically plausible: the shaking shows a gentle back-and-forth oscillation rather than jerking or freezing, the immersion shows a smooth downward motion of the paper into the liquid, and the removal shows a smooth upward motion, with no motion reversal, stutter, or unnatural change in speed.
level_5: Everything required for a 4 holds, and in addition, the container, paper, and chart keep consistent positions and scale relative to each other and to the camera throughout: the container does not drift to a different part of the frame between shots, the hand stays within natural reach of the container and paper, and during the final comparison the paper and chart hold a constant distance and alignment to each other with no sudden shift in perspective or relative size.