Domain: Healthcare — Basic Immunology
Target concept: Antigen-antibody agglutination reaction

Video generation prompt: Place the slide on a flat surface. Add one drop of antigen suspension onto the slide. Then add one drop of corresponding antiserum near the antigen suspension. Use a clean mixing rod to gently mix the drops in a circular motion for several seconds, keeping the liquid on the slide.

Evaluation guide:
(i) Target concept: Visual demonstration of bivalent antibody-mediated lattice formation leading to macroscopic agglutination.
Minimum mechanism: Antigen must be particulate (e.g., bacterial cells or latex beads), antiserum must contain specific IgG antibodies, and mixing must enable collision frequency sufficient for cross-linking (all implied by correct visual morphology and timing).
(ii)Storyline: Frame 1–2: Static flat slide with no drops. Frame 3–4: Antigen drop appears centrally. Frame 5–6: Antiserum drop appears adjacent (right/left, same plane). Frame 7–10: Rod enters, contacts both drops, and executes uninterrupted circular mixing; agglutination clusters emerge *only after contact* and grow progressively within mixed zone. Perspective: Fixed overhead view, full slide in frame, no zoom/pan, consistent lighting, no occlusion of mixing zone.

Manual:
Experimental Procedure
1. Place clean glass slide flat on surface.
2. Add one drop of antigen suspension onto center of slide.
3. Add one drop of corresponding antiserum adjacent to antigen drop.
4. Use clean mixing rod to gently mix both drops in circular motion for several seconds.
Observation of Experimental Phenomena
After mixing, coarse granular agglutination clusters appear exclusively in the mixed zone; unmixed regions remain homogeneous.
Summary of Experimental Principles
Antigen-antibody agglutination reaction: bivalent antibodies cross-link multivalent antigens, forming visible insoluble lattices.

Prompt Grounding rubric:
level_1: No slide is shown; no antigen-suspension drop appears; no antiserum drop appears; no mixing rod is present; no mixing action happens. None of the three steps of placing the slide, adding the drops, and mixing occurs.
level_2: The slide appears but is tilted more than roughly 30° or stood on edge; only one of the two drops (antigen or antiserum) is shown; a mixing rod appears but never touches either drop; or the mixing motion happens off the slide entirely.
level_3: The slide lies flat and still; a drop of antigen suspension sits on the slide; a drop of antiserum sits next to it on the same surface, not overlapping at first; a mixing rod touches both drops and moves in a circular motion; the steps occur in order: slide placed, antigen added, antiserum added, then mixing.
level_4: Everything in score 3 holds, and additionally the two drops stay fully separate right up until mixing starts; the mixing rod never travels past the edges of the slide; no fingers, labels, or unrelated tools enter the shot at any point.
level_5: Everything in score 4 holds, and additionally the mixing rod only enters the frame after both drops are fully placed and before mixing starts; no vial cap, dropper, or pipette tip is seen touching either drop at the same time as the rod; the two drops stay next to each other, without merging, from the moment the antiserum is added until the rod first touches them; every drop has a clearly recognizable rounded shape, with no shapeless liquid smear that could be mistaken for something else.

Scientific and Causal Correctness rubric:
level_1: No clustering ever appears: the liquid stays evenly cloudy or splits into separate non-mixing streams instead; no particle clumps form at all; or the mixture's color or clarity contradicts what an antigen-antibody reaction should look like, such as turning blue or green, or a cloudiness that doesn't match a particle suspension.
level_2: Clumps do appear, but at the wrong time or place: they form before the rod starts mixing, or they appear and then sit unchanged once mixing begins, or they show up only at the outer edge of the slide rather than in the zone the rod is actually stirring; the mixture instead looks like it is dissolving or clearing rather than clumping; or the antigen and antiserum drops look identical in color and cloudiness before mixing, with no visible turbid-suspension-vs-clear-serum difference.
level_3: Coarse, grainy clumps appear only after the rod begins mixing, and they stay confined to the zone the rod has actually stirred; before mixing, the antigen drop looks visibly more turbid or milky than the clearer antiserum drop; no clumps form anywhere outside the mixed zone.
level_4: Everything in score 3 holds, and additionally the clumps keep growing in size and number as the mixing continues, rather than appearing all at once; no clump ever redissolves or breaks back apart during mixing; the antigen drop is noticeably cloudier than the antiserum drop right up until they touch.
level_5: Everything in score 4 holds, and additionally every clump has a grainy, particulate look with no thread-like strands, sheets, or ring shapes; no single, isolated, unclumped particles are left dominating the field once mixing is underway: clumps consistently involve multiple particles stuck together; the clumps get visibly denser the longer mixing continues; by the end of mixing, no part of the stirred zone is free of visible clumps.

Spatiotemporal Consistency rubric:
level_1: The slide suddenly changes position or orientation between steps; the mixing rod vanishes and reappears mid-stroke; the lighting abruptly flashes on or off; the rod's shadow jumps to a different position with no transition; a drop suddenly changes shape or size with no visible cause, such as spreading out on its own without anything touching it.
level_2: The slide stays in place but rotates noticeably during mixing; the rod's motion has two or more clearly noticeable stops, not just brief natural hesitation; the two drops merge on their own before the rod ever touches them; the rod's tip disappears behind something and reappears at a different depth; background details flicker or warp.
level_3: The slide stays fixed in position and orientation the whole time; the rod moves in one continuous circular path with no reversal, pause, or lift-off; both drops keep a clearly rounded edge until the rod first touches them; the rod is never fully hidden during mixing; the lighting stays the same brightness and direction throughout.
level_4: Everything in score 3 holds, and additionally the rod appears to move at a steady, consistent speed with no sudden bursts or slowdowns; the drop's edge deforms gradually as the rod touches it rather than instantly collapsing; the rod doesn't appear to jump depth as it passes over a drop; the liquid edges and rod outline stay sharp and continuous frame to frame with no tearing or ghosting.
level_5: Everything in score 4 holds, and additionally the slide does not visibly shift or rotate at any point in the sequence; the rod tip traces a smooth, closed, roughly circular path with no sudden angle changes; the liquid's surface edge stays continuous and unbroken throughout the mixing; the motion plays out smoothly with no freeze-frame or stroboscopic look.