Domain: Engineering — Food and Bioprocess Engineering
Target concept: Determination of Phosphorus in Food (Molybdenum Blue Method)

Video generation prompt: Pipette 2 mL of the yolk extract into a test tube, add ammonium molybdate solution and ascorbic acid, and heat in a boiling water bath for 2 minutes.

Evaluation guide:
(i) Target concept: Visual confirmation of phosphorus-dependent colorimetric reaction requiring strict reagent sequence and thermal activation.
Minimum mechanism: Yolk extract must contain orthophosphate; ammonium molybdate must be present to form intermediate; ascorbic acid must reduce intermediate; heat must be applied to accelerate reduction; blue chromophore must form only under these combined conditions.
(ii)Storyline: [Frame 0–2] Pipette approaches yolk extract container → [Frame 3–4] Tip contacts liquid surface → [Frame 5–6] Liquid drawn into pipette barrel → [Frame 7–8] Pipette moves over test tube → [Frame 9–10] Liquid dispensed into tube → [Frame 11–12] Ammonium molybdate added → [Frame 13–14] Ascorbic acid added → [Frame 15–16] Test tube placed into boiling water bath (steam visible) → [Frame 17–20] Blue color emerges uniformly in solution during sustained heating; all events occur from fixed frontal viewpoint with full visibility of tube interior and bath interface.

Manual:
Experimental Procedure
1. Pipette 2 mL yolk extract into a clean test tube.
2. Add ammonium molybdate solution.
3. Add ascorbic acid solution.
4. Place test tube in boiling water bath for 2 minutes.
Observation of Experimental Phenomena
Yolk extract solution turns homogeneous, transparent blue only after heating begins — no blue before heating, no blue without both reagents.
Summary of Experimental Principles
Phosphorus in yolk forms phosphomolybdic acid with ammonium molybdate; ascorbic acid reduces it to molybdenum blue, a stable blue complex detectable spectrophotometrically.

Prompt Grounding rubric:
level_1: None of the core elements appear together: no test tube, no pipette, no yolk extract liquid, no reagents being added, and no boiling water bath anywhere in the shot.
level_2: At least one core element appears (say, just the test tube or just the pipette), but the yolk extract is never actually transferred into the tube, no reagents are added, no heating step is shown, or the steps appear out of order (e.g., the tube enters the bath before anything has been added to it).
level_3: All core elements appear together in one scene: a pipette, a test tube, the amber-yellow yolk extract, and a boiling water bath with visible steam and a submerged tube; the pipette draws from the yolk extract and dispenses it into the test tube; two separate liquid additions follow (ammonium molybdate, then ascorbic acid), each visibly distinguishable from the amber-yellow yolk extract already in the tube as a separate liquid entering it; the tube is then placed into the boiling bath; the order shown is pipetting, then the two reagent additions, then immersion.
level_4: All 3-point conditions hold, AND each reagent addition is seen streaming in and visibly beginning to mix into the yolk extract already in the tube (not merely floating on top or appearing all at once), AND the test tube stays in the bath for the whole heating period without being lifted out or repositioned, AND the pipette withdraws cleanly after dispensing rather than lingering or dripping.
level_5: All 4-point conditions hold, AND the pipette delivers the yolk extract in one continuous release rather than several separate squirts, AND both reagents are added only once the yolk extract is already in the tube, never poured in beforehand, AND the tube stays fully submerged in the boiling bath the entire time with no part of it lifted above the waterline and no condensation blocking the view, AND the camera holds the same framing throughout with no cut, AND no extra tubes, tools, or liquids appear in the shot.

Scientific and Causal Correctness rubric:
level_1: The solution never turns blue at any point: it stays amber-yellow or colorless throughout; or the water bath is never actually heated (no steam, no bubbling); or a blue color shows up in a scenario where the yolk extract or reagents were never added.
level_2: A color change happens, but the wrong color shows up (green, purple, brown, or black instead of blue); or blue appears only as a stain on the tube wall or a solid clump rather than spreading through the liquid; or the solution is already blue before the tube ever reaches the heat; or blue appears without the reagents having been added first.
level_3: The solution turns blue only after the tube enters the boiling bath, and only in the tube holding both the yolk extract and both reagents; the blue spreads evenly through the liquid rather than sitting as a film or precipitate; steam and gentle bubbling are visible in the bath while this happens.
level_4: All 3-point conditions hold, AND the blue builds up gradually while the tube is heating rather than appearing all at once at the very start or the very end, AND the blue shade is even throughout the liquid column rather than streaky or graded, AND no yellow-brown discoloration or cloudiness appears alongside the blue.
level_5: All 4-point conditions hold, AND the blue color shows up only in this fully-reacted, heated tube: no blue appears in any other tube in the same shot, AND the blue does not fade, bleach, or shift hue once formed, AND the liquid stays clear and free-flowing with no clumping, gelling, or separation, AND the shade genuinely reads as blue rather than cyan or violet.

Spatiotemporal Consistency rubric:
level_1: The test tube or pipette suddenly appears in a different spot compared to the previous shot, or briefly vanishes only to reappear a moment later with no motion shown connecting the two; the yolk extract appears inside the tube with no visible pouring; steam is visible in the bath before the tube has actually been placed in the hot water; the lighting or the background changes with no camera movement to explain it.
level_2: The pipette tip never actually touches the yolk extract before liquid appears drawn up into it; liquid enters the tube with no visible flow or drop; a reagent bottle tips as if pouring but no liquid stream is shown; the tube enters the bath with no visible downward motion; steam appears instantly rather than rising and spreading.
level_3: The pipette's full motion plays out continuously: lowering to the yolk extract, drawing liquid up, moving over the tube, and dispensing; the ammonium molybdate and ascorbic acid bottles visibly tilt and pour with a visible stream; the tube is lowered steadily into the bath, displacing the water surface as it enters; steam rises continuously and spreads naturally rather than popping in and out.
level_4: All 3-point conditions hold, AND the pace of each action (pipetting, pouring, lowering the tube) stays even with no sudden speed-ups or frozen moments, AND nothing in the shot flickers, disappears, or reappears mid-action, AND the shadows on the tube and bath track one consistent light direction throughout, AND the tube's shape stays undistorted with a coherent reflection, AND the liquid surface keeps a natural curved meniscus the whole time.
level_5: All 4-point conditions hold, AND every motion (the pipette's travel, the pouring streams, the tube's descent) plays out as one continuous, evenly-paced action rather than a series of visible jumps, AND the poured liquid streams stay intact rather than breaking into scattered droplets inconsistent with a thin, water-like reagent, AND the rising steam thickens and thins naturally with soft, shifting edges, AND the test tube and the bath behind it keep consistent relative positioning as the shot plays out.