Domain: Healthcare — Pathophysiology
Target concept: Mycobacterium tuberculosis

Video generation prompt: Take tissue samples from Mycobacterium tuberculosis infection, perform acid-fast staining (Ziehl-Neelsen staining), and observe the sections under a light microscope.

Evaluation guide:
(i) Target concept: Visual confirmation of acid-fast bacilli via Ziehl-Neelsen staining in M. tuberculosis infection.
Minimum mechanism: Carbol fuchsin must bind selectively to mycolic acid; acid alcohol must remove dye only from non-acid-fast material; methylene blue must differentially stain decolorized background; red rods must morphologically match M. tuberculosis (slender, non-beaded, non-branching).
(ii)Storyline: [Phase 1: Tissue placement] Fragment lands centrally on slide with moist texture. [Phase 2: Primary stain] Carbol fuchsin poured → spreads evenly → heated (steam visible) → cooled. [Phase 3: Decolorization] Acid alcohol applied → immediate color washout from background → red rods persist. [Phase 4: Counterstain] Methylene blue floods slide → background turns uniform pale blue → rods remain vivid red. [Phase 5: Observation] Slide mounts under microscope → eyepiece view zooms smoothly into high-power field → red rods appear isolated, slender, and sharply defined against blue background. Perspective remains fixed overhead for procedure, then shifts to simulated ocular view for final observation; all phases visible without cuts or viewpoint jumps.

Manual:
Experimental Procedure
1. Place Mycobacterium tuberculosis-infected tissue fragment onto clean glass slide.
2. Flood with carbol fuchsin, heat gently until steam rises, then cool.
3. Rinse with acid alcohol to decolorize non-acid-fast elements.
4. Counterstain with methylene blue.
5. Blot dry, mount on microscope stage, observe under 100× oil immersion.
Observation of Experimental Phenomena
Acid-fast bacilli appear as bright red, slender, straight or slightly curved rods against a pale blue background; no branching, beading, or clumping.
Summary of Experimental Principles
Mycobacterium tuberculosis has mycolic acid–rich cell walls that resist conventional stains; carbol fuchsin penetrates under heat, binds irreversibly, and resists acid-alcohol decolorization; methylene blue stains background elements, enabling high-contrast identification of acid-fast organisms.

Prompt Grounding rubric:
level_1: None of the six required objects (tissue sample, carbol fuchsin bottle, acid alcohol bottle, methylene blue bottle, glass slide, microscope) is ever shown, and none of the four core actions -- (1) tissue placed on slide, (2) carbol fuchsin applied, (3) acid alcohol decolorization, (4) methylene blue counterstain -- is performed at any point.
level_2: At least one of the six required objects appears (for example the glass slide or the microscope), but at most two of the four core actions are completed with visible reagent contact, or the actions that do occur happen out of order -- e.g., a reagent bottle is shown without ever pouring onto the tissue or slide, or the microscope appears with no slide ever placed on its stage.
level_3: All six required objects -- tissue sample, carbol fuchsin bottle, acid alcohol bottle, methylene blue bottle, glass slide, microscope -- appear on screen, and at least three of the four core actions occur in the correct order (tissue placement, then carbol fuchsin, then acid alcohol, then methylene blue), but one action is skipped or shown out of order, or the slide is never subsequently viewed through the microscope eyepiece.
level_4: All six required objects appear, and all four core actions occur in the correct order with visible reagent contact on the tissue/slide (tissue placed, then carbol fuchsin applied, then acid alcohol rinse, then methylene blue counterstain), the slide is mounted on the microscope stage, and an eyepiece view of the slide is shown at some point -- but the shift into that eyepiece view happens as a single abrupt cut with no zoom, or the eyepiece view appears only briefly before the video ends.
level_5: Everything required at level 4 is present, and in addition the eyepiece view is reached through a visible magnification transition from a wide shot of the whole slide down to a close high-power field, that close-up view is held on screen long enough to be clearly examined, and no procedural step is repeated, skipped, or shown out of the tissue-placement-then-carbol-fuchsin-then-acid-alcohol-then-methylene-blue-then-microscopy order.

Scientific and Causal Correctness rubric:
level_1: No red-stained rod-shaped structures appear anywhere in the field, and the background never turns blue -- it stays unstained white/grey, or turns entirely one uniform color with no red visible at all.
level_2: Some red coloring appears, but not on distinct rod shapes (e.g., red blobs, smears, or streaks instead of rods); or red rods appear with no blue background ever forming; or a blue background forms with no red rods on it; or the rod color reads as purple, pink, or orange rather than red.
level_3: Red, rod-shaped structures are visible, but the background is not blue (e.g., it stays white, grey, or yellow); or the red rods are noticeably bent, forked, or beaded rather than slender rods; or the rods are obscured by heavy debris/mucus that hides their shape; or the background looks artificially darkened to fake contrast rather than genuinely turning blue.
level_4: The red rods are slender, straight or gently curved, unbranched, unbeaded, and either isolated or loosely aligned in parallel; the background is a uniform pale blue; none of the rods are clumped together, broken into fragments, or covered by leftover dark-red carbol fuchsin residue -- but one or two rods show a faint bluish tinge at their ends or slightly blurred edges.
level_5: All rods are distinctly red with no hue shift toward purple or orange, uniformly slender (length at least five times width), straight or gently curved with no kinks or branching, unbeaded, unfragmented, and clearly separated from one another; the background is a uniform pale blue with no red contamination, no colorless unstained patches, no over-decolorized ghost rods, and no leftover dark-red precipitate anywhere in the field.

Spatiotemporal Consistency rubric:
level_1: The tissue sample or slide changes stain color with no reagent bottle ever shown touching it, the microscope's on-screen image jumps to a completely different field with no transition at all, the glass slide visibly cracks or the rods visibly dissolve and the video later shows them intact again, or the lighting on the slide and reagent bottles switches abruptly between bright and dark from one frame to the next with no visible cause.
level_2: At least one major continuity failure occurs short of the level above: for example, a reagent bottle tilts and appears to pour but no liquid stream ever reaches the slide, the microscope's focus knob turns while the eyepiece image itself never changes, the slide leaves the frame and returns in a different position on the stage, or a color change on the slide is shown before the reagent responsible for it has appeared on screen.
level_3: The tissue sample, slide, three reagent bottles, and microscope keep the same positions relative to each other, and each reagent's approach to the slide (bottle tilts, liquid stream forms, contact is made, bottle withdraws) plays out as one continuous motion -- with at most one brief exception, such as the shift into the microscope eyepiece view happening as a single cut rather than a gradual zoom.
level_4: Everything described at level 3 holds with no exception: the shift into the eyepiece view is itself a gradual zoom rather than a cut, the light on the slide and bottles neither brightens nor dims abruptly between the staining steps and the microscopy shot, and every reagent's liquid stream is visibly continuous from bottle tip to slide surface before any color change appears -- but one very brief irregularity remains, such as the outline of a liquid stream flickering for a single instant mid-pour.
level_5: Every transition in the video is continuous with no exception at all: the tissue sample's placement, each reagent's pour and contact, the counterstain, and the shift into the eyepiece view all play out as unbroken motion; the slide's position and wetness change gradually rather than in jumps; the light on the slide and bottles never brightens or dims abruptly at any point in the sequence.