Domain: Healthcare — Digestive Physiology
Target concept: Amylase Activity Assay (Starch-Iodine Method)

Video generation prompt: Place the starch solution into two test tubes separately. Add fresh saliva to one test tube and distilled water to the other. Let both test tubes stand undisturbed for a short period. Then add iodine solution drop by drop to both test tubes. Demonstrate the clear and simple hand operations using test tubes and pipettes.

Evaluation guide:
(i) Target concept: Enzymatic hydrolysis of starch by salivary α-amylase, visualized via iodine complex disruption.
Minimum mechanism: Starch must be present in both tubes initially; amylase must be present *only* in saliva; iodine must be added *after* enzymatic reaction period; iodine-starch complex formation requires intact helical starch structure.
(ii)Storyline: Frame 1–2: Two empty test tubes enter view, fixed side-by-side. Frame 3–4: Pipette draws liquid from labeled saliva container → deposits into left tube. Frame 5–6: Pipette draws liquid from labeled distilled water container → deposits into right tube. Frame 7: Brief pause (no action, no movement) implying incubation. Frame 8–9: Iodine dropper approaches left tube → releases 2–3 discrete droplets → liquid color changes to pale yellow/amber. Frame 10: Iodine dropper approaches right tube → releases 2–3 discrete droplets → liquid color changes to or remains deep blue-black. All actions occur from fixed frontal viewpoint; no object leaves frame; liquid surfaces fully visible during all color observations.

Manual:
Experimental Procedure
1. Place two identical transparent test tubes side-by-side.
2. Using a clean pipette, add fresh saliva to the first tube.
3. Using a clean pipette, add distilled water to the second tube.
4. Let both tubes stand undisturbed briefly, giving the enzyme time to act before iodine is added.
5. Add iodine solution drop-by-drop to both tubes.
Observation of Experimental Phenomena
The tube with saliva becomes pale yellow/amber/colorless; the tube with distilled water remains deep blue-black.
Summary of Experimental Principles
Salivary amylase hydrolyzes starch into maltose, destroying the starch-iodine complex; intact starch binds iodine to produce blue-black color.

Prompt Grounding rubric:
level_1: No test tubes are shown; no pipette appears; neither a saliva container nor a distilled water container is shown; no iodine bottle appears; no hand is shown performing any transfer or addition.
level_2: At least one test tube appears, but the two tubes are never shown together in the same frame; a saliva or distilled water container appears but not both; a pipette is shown but never actually touches or transfers any liquid; the iodine bottle is absent, or is never shown dispensing into a tube.
level_3: Two test tubes appear side by side; a container for saliva and a separate container for distilled water are both visible; a pipette moves liquid from one of the sources into one of the tubes, but the order of steps is confusing; for instance, iodine drops appear in a tube before both saliva and water have actually been added, or before the tubes are given any time to sit, so it looks like the amylase never gets a chance to act before iodine shows up.
level_4: Two test tubes stand side by side and do not move; saliva is drawn from its container and placed only in the first tube, and distilled water is drawn from its container and placed only in the second tube; a short, visible pause with no action follows before the iodine dropper appears, and iodine is added drop by drop to both tubes only after that pause; one minor slip is still present, such as: (a) a hand blocks the view of a tube's liquid right as iodine is added, or (b) the pipette tip brushes the inside wall of a tube during a transfer, or (c) the iodine falls as a thin stream rather than distinct drops in one of the tubes.
level_5: Two identical clear test tubes sit side by side in a steady, front-facing view; saliva from one labeled container goes only into the left tube, and distilled water from a separate labeled container goes only into the right tube; after both liquids are added, the tubes are shown sitting undisturbed for a clearly visible pause before the iodine dropper enters the frame; iodine is then added drop by drop to both tubes, one after the other, with the liquid surface of each tube fully visible during every drop; no tube, container, or the iodine bottle ever disappears, duplicates, or is blocked from view at a key moment.

Scientific and Causal Correctness rubric:
level_1: After iodine is added to both tubes, neither shows the expected contrast (for example, both tubes turn the same deep blue-black, or both stay pale and colorless), so there is no visible sign that the saliva broke down the starch while the water left it intact.
level_2: Only one of the two tubes changes color when iodine is added, but the pattern is backwards or wrong; for example, the saliva tube turns blue-black as if its starch were still intact, while the water tube stays colorless, or both tubes turn the same shade; or a color change shows up in a tube before iodine has actually reached its liquid.
level_3: The saliva tube loses its capacity to turn blue-black (ending up pale yellow, amber, or colorless after iodine is added) while the water tube does develop a blue-black color; the expected contrast is present, but it's hard to see clearly, for instance because the colors look washed out, overexposed, or too close in brightness to tell apart with confidence.
level_4: The saliva tube shows no trace of blue-black anywhere in its liquid after iodine is added, staying pale yellow, amber, or colorless throughout, while the water tube turns a clear, even blue-black across its entire liquid column after iodine is added; both color states hold steady long enough to compare the two tubes side by side.
level_5: The saliva tube's liquid is uniformly free of any blue-black tint after iodine is added (pale yellow, amber, or colorless throughout, with no streaks of blue), and the water tube's liquid is uniformly blue-black from top to bottom with no patchy spots; both colors stay steady for at least a couple of seconds after the drops are added, with no in-between shades, making the contrast between the amylase-treated tube and the untouched-starch tube unmistakable.

Spatiotemporal Consistency rubric:
level_1: A test tube suddenly appears in a new spot with no continuous motion connecting where it was before; the pipette drops out of the shot mid-transfer and returns already empty or already full a moment later; an iodine droplet hangs still in mid-air and then jumps to a new position; the whole scene snaps from normal lighting to near-total darkness or back between consecutive frames; a tube's glass abruptly bulges or narrows with no visible cause.
level_2: A test tube shifts or spins noticeably from one shot to the next with no hand ever touching it; the pipette tip moves on its own, detached from the hand holding it; an iodine droplet's path bends sideways in mid-air instead of falling straight down; the background behind the tubes flickers or warps; the liquid surface sloshes in a way that doesn't match any addition or movement actually shown.
level_3: Both test tubes stay in place, the pipette moves smoothly from each source to its tube, iodine droplets fall in a natural, slightly curved path into each tube, and each liquid surface settles normally after every addition; but one small slip appears, such as the base of a tube being briefly hidden by the pipette during a transfer, or a single moment where a hand blocks the view of both tubes at once.
level_4: The two test tubes hold the same position, height, and tilt throughout; the pipette's movement from container to tube is continuous and looks physically natural; each iodine droplet descends smoothly and lands near the center of its tube; the liquid surface in each tube forms and settles naturally after each addition, with no key moment (a tube's opening, its liquid surface, or its resulting color) ever hidden from view; only an inconsequential flaw remains, such as a faint, brief glint of reflection off a tube wall lasting under a second.
level_5: All 4-point conditions are met, and in addition: the tubes stay in the same position and size relative to each other across the whole clip; the pipette's motion looks fully natural and matches how a hand would actually move; every iodine droplet follows a smooth, unbroken path into its tube; each liquid surface's shift from calm, to disturbed by the drop, to calm again reads as continuous and physically believable; there is no flicker, no warped geometry, and no sudden change in lighting anywhere from the first frame to the last.