Domain: Healthcare — Digestive Physiology
Target concept: Bile Emulsification Assay (Simulative Method)

Video generation prompt: Place oil and water into a transparent test tube and gently shake. Add the simulated bile solution, cap the test tube, and shake again. Use a transparent container and pipette to carry out each step. Show the full procedure and how the liquid's appearance changes as a result, without adding on-screen text, narration, or labels that state the scientific conclusion.

Evaluation guide:
(i) Target concept: Bile-mediated stabilization of oil-in-water emulsion via interfacial tension reduction.
Minimum mechanism: Oil and water must be immiscible and visually distinguishable; bile solution must be delivered into the same aqueous environment; mechanical agitation must precede bile action to generate initial droplets; bile must act *after* agitation to prevent coalescence and sustain dispersion.
(ii)Storyline: Frame 1–2: Static shot showing oil (upper layer, less dense, higher meniscus, slight yellow tint) and water (lower layer, neutral clarity) in transparent vertical test tube. Frame 3–4: Tube undergoes gentle oscillatory shake; oil disperses as transient cloudy suspension, then rapidly re-coalesces into two sharp layers. Frame 5: Pipette enters frame from top-right, tip aligned with tube opening. Frame 6: Bile solution dispensed as cohesive stream into tube. Frame 7: Cap approaches and seals tube mouth. Frame 8–9: Same tube shaken identically; mixture becomes uniformly cloudy/milky and remains so without resurfacing oil droplets or layering. Fixed frontal viewpoint throughout; no cuts; all objects remain in consistent spatial relation.

Manual:
Experimental Procedure
1. Place oil and water into a transparent test tube.
2. Gently shake the tube to mix.
3. Add simulated bile solution using a pipette, cap the tube, and shake again.
Observation of Experimental Phenomena
Before shaking: oil and water form two distinct layers.
After first shake: temporary cloudy mixture that quickly separates back into layers.
After bile addition and second shake: stable cloudy/milky emulsion with no phase separation.
Summary of Experimental Principles
Bile salts act as biological emulsifiers—reducing surface tension between oil and water, enabling formation of small, stable oil droplets suspended in water (emulsion).

Prompt Grounding rubric:
level_1: No transparent test tube appears; or no oil, water, or bile solution is visible; or neither the pipette nor a capping action appears; or no shaking motion happens at any point; none of the procedure's three stages (loading oil and water, the first shake, adding bile and shaking again) occurs.
level_2: At least one correct item is present (the tube, the pipette, or a liquid), but none of the three procedural stages is actually carried out; the liquids look like a single uniform fluid rather than distinguishable oil and water; the tube is never capped; no shake ever occurs.
level_3: The tube holds two visibly distinct liquids (oil sitting above water, or otherwise visually separable), and the bile solution appears via the pipette or is shown already dispensed; the tube is shaken once with only oil and water inside, the bile solution is then added, the tube is capped, and it is shaken a second time; all three stages occur in that order.
level_4: Everything needed for score 3 is present, plus: the oil and water are loaded into the same tube before the first shake; the pipette delivers the bile solution into that same tube, not a different container; the cap is placed on that same tube; both shakes are performed on the identical tube from the same camera framing; no extra tube, container, or liquid appears.
level_5: Everything needed for score 4 is present, plus: the seven stages happen in strict order with nothing skipped, repeated, or reversed (oil and water go into the tube, the tube is shaken, bile solution is drawn into the pipette, the pipette tip enters the tube's mouth, the bile solution is dispensed, the tube is capped, and the tube is shaken again), all within one continuous, fixed-viewpoint shot.

Scientific and Causal Correctness rubric:
level_1: No visible change occurs between the liquid's appearance before and after either shake; oil and water look like one uniform liquid throughout; the bile solution looks identical to plain water; nothing in the video suggests an emulsification process is happening.
level_2: Oil and water are visibly separate before the first shake (e.g., layered), but shaking produces no change in their appearance and they stay fully separated; the bile solution is added, but the mixture's dispersion state never changes afterward; there is no visible link between adding the bile solution and any change in how the liquids mix.
level_3: Oil and water sit as two clear layers before the first shake; the first shake turns them briefly cloudy or milky, and they separate back into two clear layers soon after shaking stops; after the bile solution is added and the tube is shaken again, the mixture stays uniformly cloudy or milky, with no layers reappearing for the rest of the clip.
level_4: Adding to the 3-point description: the pre-bile shaken mixture is only briefly cloudy before quickly clearing, while the post-bile shaken mixture stays cloudy or milky without oil droplets resurfacing or layers reforming; the liquid's color and texture stay consistent with an oil-water-bile mixture, with no yellowing, curdling, or solid material appearing.
level_5: Adding to the 4-point description: the first, pre-bile cloudiness appears only while the tube is being shaken and clears almost immediately once shaking stops; the second, post-bile cloudiness appears only once the bile solution has been added and shaking resumes, then persists for the rest of the clip with no oil droplets rising, no meniscus reforming, and no visible oil-water interface re-emerging.

Spatiotemporal Consistency rubric:
level_1: The test tube jumps from one position or orientation to another between frames; the lighting changes suddenly for no reason tied to the action; the liquid's surface changes shape in a way that matches no pouring or shaking motion; the cap appears or disappears with no hand moving it; the pipette tip appears to pass through the tube's wall instead of entering its mouth.
level_2: The tube rotates more than roughly a quarter turn with no visible hand causing it; the liquid level changes suddenly with no pouring or shaking to explain it; the cap seems to snap onto or off the tube without contact; the pipette appears already inserted into the tube with no approach motion shown; the background changes between shots; the camera's framing changes partway through, e.g., jumping from a close-up to a wide shot.
level_3: A brief cut between the first shake and the bile-addition step is acceptable, provided the tube's position, tilt, and liquid volume match exactly on both sides of the cut; the lighting stays the same before and after the cut; neither the tube nor the liquid warps or jumps location; the tube, pipette, and cap all stay the same size and in the same place relative to one another throughout.
level_4: Layered onto the 3-point requirements: every motion looks physically natural; the shaking resembles an actual wrist movement rather than a mechanical back-and-forth; the pipette approaches the tube's opening along a smooth path; the cap seats onto the tube's mouth without visibly missing it or clipping through it; how the liquid sloshes matches the direction and force of each shake.
level_5: Layered onto the 4-point requirements: the entire sequence plays out as one continuous, uncut shot with the tube held steady at the center of the frame and no pan, tilt, or zoom; the liquid's surface changes shape smoothly, frame to frame, during each shake; the cap visibly meets the tube's threads before it is fully closed; the pipette enters the frame from the same off-screen position each time and releases the bile solution with no splatter or floating droplets.