Domain: Healthcare — Nutrition and Food Hygiene
Target concept: Determination of Cadmium in Heavy Metals

Video generation prompt: A 10 mL water sample with cadmium ion concentration exceeding the standard was placed in a test tube. p-Nitrobenzene diazoaminodiazobenzene was added to the test tube, and the pH was adjusted to 11 with sodium hydroxide. The test tube was shaken uniformly and then allowed to stand. The scene was continuously photographed for about 10 to 15 seconds.

Evaluation guide:
(i) Target concept: Formation of a pH-dependent, colored metal-chelate complex for cadmium detection.
Minimum mechanism: Cadmium ion must be present in aqueous solution; chelating reagent and strong base must be sequentially introduced; molecular binding requires mixing and alkaline activation to produce visible red-violet chromophore.
(ii)Storyline: Frame 1–2: Static shot of labeled test tube containing clear water sample. Frame 3–4: Bottle of orange-red reagent approaches and dispenses liquid into tube. Frame 5–6: Second bottle (colorless) dispenses NaOH into same tube. Frame 7: Hand grasps tube and performs smooth rotational shake (liquid swirls visibly). Frame 8–10: Tube placed upright on surface; liquid settles, red-violet color emerges and deepens uniformly across column; no motion or external interference. Perspective: Fixed frontal view, eye-level, centered on test tube; all actions occur within same continuous frame without cut or repositioning.

Manual:
Experimental Procedure
1. Place 10 mL cadmium-containing water sample in clean test tube.
2. Add p-Nitrobenzene diazoaminodiazobenzene reagent.
3. Add sodium hydroxide solution to adjust pH to 11.
4. Shake test tube uniformly.
5. Stand test tube upright and observe continuously.
Observation of Experimental Phenomena
A distinct red-violet color develops in the solution after shaking and intensifies during standing; no precipitate forms; color is uniform and stable.
Summary of Experimental Principles
Cadmium ions form a red-violet chelate complex with p-Nitrobenzene diazoaminodiazobenzene under strongly alkaline conditions (pH 11), enabling qualitative detection.

Prompt Grounding rubric:
level_1: No test tube or water sample is shown; or neither the reagent bottle nor a liquid-addition action appears; or no sodium hydroxide container or pH-adjustment action appears; or the tube is never shaken or left standing; or the footage does not read as one continuous take.
level_2: The test tube with clear liquid is shown, but no 10 mL volume marking is identifiable; only one reagent bottle appears with no visible pour into the tube; the sodium hydroxide container never appears; and neither a shake nor a standing sequence is shown.
level_3: The test tube holding the clear cadmium water sample is shown; the p-Nitrobenzene diazoaminodiazobenzene reagent is visibly poured in from a distinct bottle; the sodium hydroxide solution is then visibly added from a separate bottle; the tube is shaken by hand (visible motion plus liquid swirling) and then set upright and held still for at least a couple of seconds.
level_4: Everything required at the 3-point level holds, and in addition: the test tube's size and markings read as a standard 10 mL vessel; the reagent bottle (orange-red liquid) and the NaOH bottle (colorless liquid) are visually distinct from one another; the shake happens right after both liquids are added, followed by a clearly still period with no further hand or tube motion.
level_5: Everything required at the 4-point level holds, and in addition: the test tube stays in the same spot on screen for the whole video with no panning or repositioning; the reagent and the NaOH are added one after the other without overlapping; the shaking looks like an even rotational swirl rather than jerky or partial motion; the liquid inside comes fully to rest before the video ends; the bottles and tube stay in the same plane and arrangement throughout, with nothing floating or misaligned.

Scientific and Causal Correctness rubric:
level_1: The liquid in the test tube never changes color from clear to red-violet; or a precipitate or color appears before any reagent is added; or the reagent is shown reacting with something other than the water sample (e.g., a solid or a gas).
level_2: A color change does happen, but it's the wrong color (blue, green, or purple instead of red-violet), or the color shows up before the sodium hydroxide is added, or a precipitate forms and it is white or yellow rather than the expected red-violet.
level_3: A red-violet color appears in the test tube after the shake, during the standing phase; the color sits within the liquid itself (not smeared on the tube wall or cap); the solution stays clear/homogeneous with no visible precipitate; the color only shows up after both the reagent and the NaOH have been added and the tube has been shaken.
level_4: Everything required at the 3-point level holds, and in addition: the red-violet color visibly deepens as the standing phase continues; no color is present before the NaOH is added; the color does not appear as soon as the liquids are poured but only after the mixing/shake has happened; the color doesn't fade or shift to a different hue while standing.
level_5: Everything required at the 4-point level holds, and in addition: the red-violet color fills the whole liquid column evenly, with no lingering paler or darker layers within the liquid; the color reaches its full, deepest intensity well before the video ends and stays stable for the remainder of the clip; the opening frames clearly show the liquid colorless before the reagent and before the NaOH are added; the sequence of pour reagent → pour NaOH → shake → color appears → color deepens → color stabilizes plays out with no step skipped or out of order.

Spatiotemporal Consistency rubric:
level_1: The test tube vanishes and reappears somewhere else with no visible path between; or the liquid jumps from one container to another; or the screen suddenly flashes or goes dark; or the camera abruptly jumps to a different zoom or angle; or the test tube visibly bends or shatters with no cause; or the liquid's surface flips to face the wrong way.
level_2: The test tube stays visible but shifts noticeably from its earlier position between moments in the video; the liquid's surface curve looks inconsistent from one moment to the next; the shadow direction changes without any change in the light source; or the shaking motion visibly skips ahead, losing several frames' worth of continuity.
level_3: The test tube stays in the same spot throughout; the liquid level stays constant with no unexplained spilling or evaporation; the meniscus curve looks physically normal and consistent; shadows keep pointing the same direction; the shake looks like a smooth speeding-up and slowing-down motion; once the tube is set down, any ripples on the liquid surface gradually settle rather than stopping abruptly.
level_4: Everything required at the 3-point level holds, and in addition: the reagent bottle, NaOH bottle, and test tube keep a stable arrangement relative to each other on the same surface; there's no flicker or strobing between frames; the liquid's surface moves the way a real fluid would during the shake (no rigid spinning or instant stop); the ripple decay after shaking looks gradual with no abrupt jump implying skipped frames.
level_5: Everything required at the 4-point level holds, and in addition: the relative sizes and spacing of the tube, bottles, and hand stay geometrically consistent across the whole video; reflections of light on the liquid surface stay consistent rather than flashing oddly; the test tube shows no visible shaking or vibration during the standing phase; motion blur during the shake points in the direction of motion and scales with how fast the tube is moving; the tube never appears to pass through the hand or the bottles during the pouring or shaking actions.