Domain: Healthcare — Nutrition and Food Hygiene
Target concept: Strychnine Detection

Video generation prompt: A 10-mL food extract containing strychnine was placed in a test tube, followed by the addition of concentrated sulfuric acid and a small crystal of potassium dichromate. The mixture was thoroughly shaken and allowed to stand.

Evaluation guide:
(i) Target concept: Colorimetric detection of strychnine using the concentrated sulfuric acid–potassium dichromate color test.
Minimum mechanism: Strychnine must be present in the food extract; the sulfuric acid and potassium dichromate must both be added after the extract; shaking brings the reagents into contact with the extract; standing lets the resulting color sequence run its course and settle into a stable final hue; the color change depends on the oxidizing dichromate acting on strychnine under strongly acidic conditions.
(ii)Storyline: [Phase 1] Static shot: empty test tube enters frame → [Phase 2] 10-mL food extract poured in (visible meniscus rise) → [Phase 3] Concentrated sulfuric acid and a small crystal of potassium dichromate are added (second meniscus rise, a cloudy swirl where the dense acid meets the extract) → [Phase 4] Hand shakes tube (liquid turbulent, walls blurred slightly) → [Phase 5] Tube placed down, liquid agitation settles to full stillness → [Phase 6] A color emerges and shifts through a brief sequence before settling into a stable final hue. Perspective: fixed frontal view, shallow depth of field, full test tube in frame throughout; no cutaways, no POV shifts, no object occlusion during critical phases.

Manual:
Experimental Procedure
1. Place 10-mL food extract into a clear glass test tube.
2. Add concentrated sulfuric acid and a small crystal of potassium dichromate to the test tube.
3. Shake the test tube, then set it down to stand.
Observation of Experimental Phenomena
A brief sequence of colors passes through the liquid after the reagents are added and mixed — starting bluish-violet, moving to red, and settling into a stable orange-yellow that persists through the standing period; no precipitate, gas, or layering occurs.
Summary of Experimental Principles
Under strongly acidic conditions, the oxidizing dichromate ion reacts with strychnine, producing a short-lived sequence of colors (bluish-violet, then red, then orange-yellow) that is used as a classical qualitative color test for strychnine in food-safety and forensic toxicology analysis.

Prompt Grounding rubric:
level_1: No test tube is shown; no food extract is visible; no sulfuric acid or potassium dichromate is shown being added; no shaking or standing takes place; none of the three needed items (the test tube, the food extract, and the acid/dichromate reagent) appear.
level_2: At least one item appears (e.g., just the test tube on its own), but none of the needed actions happen: the 10-mL food extract is never placed in the tube, the sulfuric acid and dichromate are never added, no shaking is shown, no standing period is shown; the sequence is missing steps or shown out of order; the reagent and the extract never appear together in the same tube.
level_3: All three needed items appear: the test tube, the food extract (a clear-to-amber liquid), and the sulfuric acid–dichromate reagent (added as a dense, near-colorless liquid together with a small orange dichromate crystal or grains); the extract is placed in the tube, then the reagent is added; a shaking action is shown; a standing phase follows with the liquid at rest; all in one continuous, fixed-camera shot.
level_4: Everything from the 3-point level holds, and the order is preserved throughout: the extract goes in first, then the reagent, then shaking happens, then standing follows; both the extract and reagent stay visibly inside the test tube the entire time; nothing about the tube or its contents is duplicated, swapped out, or hidden from view.
level_5: Everything from the 4-point level holds, and the five stages play out in strict, unambiguous order with no overlap: (1) extract placed in the tube, (2) sulfuric acid and dichromate added, (3) vigorous shaking with the liquid visibly turbulent and the meniscus disturbed, (4) the shaking stops, (5) the liquid fully settles with a steady meniscus; each stage clearly starts and ends before the next begins, with no stage skipped.

Scientific and Causal Correctness rubric:
level_1: No color appears at all after the acid and dichromate are added, and the liquid stays completely unchanged before and after shaking and standing; or what appears has nothing to do with the expected bluish-violet/red/orange-yellow sequence (e.g., the liquid simply turns uniformly black, or stays clear throughout).
level_2: Some color or turbidity shows up, but it clashes with the expected reaction: for example the liquid jumps straight to orange-yellow with no earlier violet or red stage, or a color appears before the dichromate is even added, or the color only shows up during the shaking itself and is gone once the tube is set down to stand.
level_3: After the sulfuric acid and dichromate are added and the tube is shaken, the liquid passes through a brief color sequence (starting bluish-violet, moving to red, and settling into orange-yellow), and that final orange-yellow color persists through the standing period; the color fills the liquid evenly with no floating solid bits or sediment; nothing else odd happens (no gas bubbles, no charring, no glow).
level_4: Everything from the 3-point level holds, and the color sequence only begins once both the sulfuric acid and dichromate have been added and the tube has been shaken, not before; the final orange-yellow shade looks the same strength up and down the liquid column, without one section a noticeably different shade than another; nothing else competes with it, like a green tinge or patches of cloudiness unrelated to the color change.
level_5: Everything from the 4-point level holds, and the final orange-yellow color stays confined to the liquid inside the tube, with a crisp boundary at the liquid's surface rather than any haze or color creeping up the glass above the liquid line; the color holds steady and even for the entire standing period, without fading, darkening further, or separating into layers.

Spatiotemporal Consistency rubric:
level_1: The test tube blinks out of the shot and comes back moments later; the liquid inside jumps from one level or position to another between cuts; the room's lighting suddenly changes brightness mid-clip; the wall or table behind the tube bends or warps; the camera angle itself changes (zooming, panning, or rotating) partway through the clip.
level_2: The test tube shifts position, or the liquid level changes, without any addition or removal to explain it; the shaking motion looks jerky, with droplets seeming to hop from spot to spot rather than fly and fall continuously; during the standing phase the liquid surface keeps rippling or bobbing instead of settling down; the tube itself appears to bend or twist in a way rigid glass couldn't.
level_3: The test tube stays in the same spot in the frame throughout; the liquid volume looks the same before and after each addition, with no unexplained spilling or shrinking; the shaking phase shows the liquid moving and sloshing in a way that connects smoothly frame to frame, and it settles down gradually rather than stopping instantly.
level_4: Everything from the 3-point level holds, and the turbulence from shaking dies down smoothly and steadily rather than cutting off abruptly; there's no flickering, ghosting, or blur so heavy that the tube's edges become impossible to make out; the reflections of light on the liquid's surface shift smoothly as it moves and settle down consistently once it's still.
level_5: Everything from the 4-point level holds, and the test tube's walls stay straight and parallel in every frame; the curve of the liquid's meniscus against the glass looks consistent with how liquid actually sits against glass; there's no visible lens warping or rolling-shutter skew; every transition (the start and stop of the shaking, the rise and settling of ripples) flows smoothly, moving the way real liquid and glass would.