Domain: Healthcare — Microbiology-Immunology
Target concept: Rapid Escherichia coli Detection (Eosin-Methylene Blue Colorimetric Method)

Video generation prompt: Inoculate the *Escherichia coli* sample onto an EMB agar plate by streaking, cover the plate, invert it and incubate at 35–37°C. After incubation, remove the plate for examination. Emphasis should be placed on clear and continuous hand movements, proper handling of the agar plate, and accurate execution of the incubation procedure.

Evaluation guide:
(i) Target concept: Visual demonstration of the standardized EMB streak-and-incubate protocol for E. coli detection, where metallic green sheen on isolated colonies is the definitive visual biomarker. Minimum mechanism: EMB medium must be chemically intact and properly poured; inoculum must be viable E. coli; incubation must occur aerobically at 35–37°C for sufficient time (≥18h) to express phenotype; observer must view colonies under standard white light at oblique angle to resolve sheen.
(ii)Storyline: Frame 1–2: Hand holds sterile loop approaching EMB plate. Frame 3–4: Loop contacts agar and executes three continuous, parallel streaks. Frame 5: Lid lifts slightly then seats fully onto plate. Frame 6: Plate rotates 180° as rigid unit to invert (base now uppermost). Frame 7: Inverted plate translates into incubator viewport (label “35–37°C” visible). Frame 8: Cut to same plate retrieved; held steady, front-facing. Frame 9–10: Close-up of streak zone showing discrete colonies, one with unambiguous metallic green sheen; all under consistent frontal lighting, fixed viewpoint, no camera movement.

Manual:
Experimental Procedure
1. Streak E. coli sample in parallel lines across EMB agar surface using sterile loop.
2. Cover plate with lid.
3. Invert plate (agar base up, lid down).
4. Place inverted plate in incubator set to 35–37°C.
5. After incubation, remove plate and examine colonies.
Observation of Experimental Phenomena
Isolated colonies grow along streak lines; E. coli colonies exhibit characteristic metallic green sheen on dark purple-black EMB agar.
Summary of Experimental Principles
EMB agar contains eosin Y and methylene blue, which inhibit Gram-positive bacteria and differentiate lactose fermenters; E. coli ferments lactose vigorously, producing acid that concentrates dyes and yields metallic green sheen.

Prompt Grounding rubric:
level_1: No EMB agar plate appears; or no hand is shown streaking; or the plate is never inverted; or no incubator (or clearly labeled 35–37°C environment) appears; or there is no scene of the plate being examined after incubation.
level_2: The EMB plate is shown, but no streaking motion occurs; or the plate is inverted without ever being streaked first; or an incubator appears with no plate placed inside it; or a post-incubation plate is shown with no earlier inoculation shown. At least one of the required objects appears, but none of the actions happen in the right sequence.
level_3: The hand streaks a continuous, linear pattern onto the EMB plate; the lid is then placed onto the base; the plate is inverted (base up, lid down); the plate is placed inside an incubator that is labeled or otherwise clearly consistent with 35–37°C; after a scene transition implying incubation time, the same plate is removed and held up for examination. All five steps appear in the right order, but at least one is not fully clear (for example, the streak lines blur together, the inversion is ambiguous, or the lid placement is partly out of frame).
level_4: All five steps are shown clearly and in the right order: the hand draws continuous, evenly spaced streak lines across the agar; the lid is fully seated on the base; the plate is fully inverted with the base unmistakably on top; the inverted plate goes into an incubator with a visible temperature label or an unmistakably incubator-like appearance; and the same plate is retrieved afterward and held steady for viewing, with no step skipped, reordered, or hidden from view; only minor flaws are allowed, such as a slight hand tremor, a brief change in ambient lighting, or the single expected scene transition that marks the incubation time skip.
level_5: All five steps are executed with complete visual clarity: the streak lines are unbroken and evenly spaced across the whole agar surface; the lid seats fully and squarely; the inversion is smooth and complete with no tilt or hesitation; the plate's placement into the incubator is clearly shown as it moves onto a shelf or rack; and the plate retrieved afterward is unmistakably the same one, with no swap, extra rotation, or replacement; apart from the single expected scene-transition cut that marks the incubation time skip (which may carry a lighting change consistent with leaving the incubator), the plate, lid, and loop stay spatially and temporally consistent throughout each visible step, with no stray motion, no blocked view, no other lighting jump, and no dropped frames.

Scientific and Causal Correctness rubric:
level_1: No EMB plate appears; or the plate shown does not look like EMB (e.g., it looks like plain nutrient agar, blood agar, or an unrelated color); or no bacterial growth appears after incubation; or growth appears but is white, yellow, or otherwise non-green; none of this matches the real appearance of E. coli on EMB.
level_2: The plate is present and has the correct dark purple-black EMB color, but no streaking is shown; or streaking is shown with no post-incubation growth; or growth appears but never develops a metallic green sheen; or a sheen appears but on the wrong kind of colony (e.g., a smeared, non-isolated, or fully confluent lawn instead of separate colonies).
level_3: The EMB plate is dark purple-black; separate colonies appear along the streak lines after incubation; at least one colony shows a metallic green sheen, the correct color and colony pattern for E. coli; the sheen is clearly a property of the colony itself rather than glare from the light source; growth is confined to the streaked region rather than covering the whole plate; and nothing else on the plate looks scientifically wrong (no dominant pink colonies, no mucoid texture inconsistent with E. coli).
level_4: Everything required for a 3 also holds; in addition, the metallic green sheen appears specifically on colonies that are well separated, raised, and smooth-surfaced, sitting along the streak lines; no colony looks like a non-E. coli phenotype (no pink, mucoid-edged colonies; no colorless colonies; no spreading growth); and the background agar stays uniformly dark purple-black with no discoloration, drying, or cracking, consistent with how EMB actually differentiates lactose fermenters.
level_5: Everything required for a 4 also holds; in addition, the metallic green sheen is sharply confined to each colony's surface (no bleeding halo around it) and looks the same under the lighting used throughout the shot; the colonies are small, roughly 1–2 mm across, circular, and clearly separated from one another rather than merging into a lawn; nothing else on the plate could be mistaken for the sheen (no specular highlight sitting exactly where a colony would be, no smudge of pigment standing in for a colony); and the full causal chain (streaking, then incubation, then isolated green-sheened colonies along the streak lines) is visible with no gap in logic or time.

Spatiotemporal Consistency rubric:
level_1: The plate disappears and reappears in a different spot or orientation; the hand jumps between positions with no motion shown in between; the lid snaps onto or off the plate with no visible motion; the plate rotates or flips with nothing touching it; the light on the scene jumps suddenly partway through the sequence; or the agar surface ripples or warps in a way that is not physically possible.
level_2: One clear break in continuity occurs somewhere in the sequence: for example, the streaking motion begins in mid-air with the loop never actually touching the agar; the plate is shown inverted before the lid has been placed; the incubator door opens and the plate is simply already inside with no hand placing it there; or the plate examined after incubation shows a different label or a scratch that was not on the plate beforehand (new condensation on the lid from the incubation itself is expected and should not count against this).
level_3: The plate, lid, and loop keep a consistent identity and position throughout: the hand stays in contact with the plate surface continuously while streaking; the lid moves smoothly from off the plate to fully seated; the inversion happens as one continuous rigid motion with no bending or partial turning; the plate visibly moves into the incubator rather than appearing there; and the plate retrieved afterward has the same orientation and the same label as before incubation (new lid condensation from the incubation step is expected and not counted as an inconsistency).
level_4: Everything required for a 3 also holds; in addition, all motion (hand, lid, plate) looks smooth and physically plausible, without jerking, floating, or sudden speed changes; the loop visibly presses into the agar slightly while streaking rather than hovering above it or sinking through it; the hand never fully blocks the plate during any of the five key actions; and the direction and softness of the shadows stay the same from the streaking step through the retrieval step.
level_5: Everything required for a 4 also holds; in addition, there is no ghosting or motion blur that looks inconsistent with how fast something is moving; the lid's edge stays visibly sharper than the agar surface, and the plate's base visibly sits in front of the lid once inverted; every object's outline stays crisp and unbroken from frame to frame; and the streaking, inversion, and incubation-to-retrieval cut all take a consistent, natural amount of screen time with no jarring speed-up or freeze.