Domain: Healthcare — Microbiology-Immunology
Target concept: Nisseria meningitidis Detection (Gram Stain and Oxidase Test)

Video generation prompt: Prepare a smear of Neisseria meningitidis on a glass slide, perform heat fixation, sequentially apply Gram staining reagents and gently rinse, and observe under the microscope. Subsequently, demonstrate the picking of colonies, applying oxidase reagent onto filter paper, and observe the immediate detection process.

Evaluation guide:
(i) Target concept: Visual verification of two definitive identification tests for Neisseria meningitidis: Gram stain morphology and oxidase enzyme activity.
Minimum mechanism: Bacterial cells must be physically present on slide and filter paper; heat fixation must alter cell adhesion without lysis; Gram reagents must interact sequentially with cell wall components to yield differential staining; oxidase reagent must chemically react with bacterial enzyme to produce chromogenic product.
(ii)Storyline: [Frame 0–1] Sterile loop contacts visible bacterial colony on agar surface. [Frame 2–3] Loop drags across glass slide, leaving thin translucent film. [Frame 4–5] Slide passes through steady flame; no smoke, no warping. [Frame 6–7] Crystal violet floods slide surface, evenly coats. [Frame 8–9] Iodine solution applied, forms visible complex. [Frame 10] Alcohol stream removes violet from Gram-negative cells. [Frame 11] Safranin stains remaining cells pink/red. [Frame 12] Microscope eyepiece view centers on field showing discrete, adjacent, kidney-bean-shaped pink/red diplococci. [Frame 13] Loop picks new colony. [Frame 14] Loop deposits colony onto white filter paper. [Frame 15] Oxidase reagent droplet falls, spreads, and transforms entire wetted area to deep purple-black within same continuous view; no cut, no delay, no fade.

Manual:
Experimental Procedure
1. Use sterile loop to pick Neisseria meningitidis colony.
2. Spread loop across clean glass slide to prepare thin smear.
3. Air-dry, then pass slide through flame 2–3 times for heat fixation.
4. Flood with crystal violet (10–20 s), rinse gently.
5. Flood with iodine (10–20 s), rinse gently.
6. Decolorize with alcohol (1–3 s), rinse immediately.
7. Counterstain with safranin (30–60 s), rinse gently.
8. Blot dry, observe under oil immersion microscope.
9. Pick fresh colony, transfer to filter paper.
10. Apply oxidase reagent drop; observe purple-black color developing within seconds.
Observation of Experimental Phenomena
- Microscope: pink/red, kidney-bean-shaped diplococci, no chains or rods.
- Oxidase test: filter paper develops a uniform, deep purple-black color within about 10–20 seconds of reagent contact (a strongly oxidase-positive reaction).
Summary of Experimental Principles
- N. meningitidis is Gram-negative (pink/red after full Gram stain) and oxidase-positive (rapid purple-black oxidase reaction). Gram stain differentiates based on peptidoglycan thickness; oxidase test detects cytochrome c oxidase enzyme activity.

Prompt Grounding rubric:
level_1: None of the ten manual steps appear at all: no glass slide, no bacterial colony or smear, no flame or heat-fixation pass, no crystal violet/iodine/alcohol/safranin containers, no microscope, no filter paper, and no oxidase reagent dropper are shown at any point.
level_2: A single prop from the procedure is visible (for example just a glass slide, or just a filter paper, or just a reagent dropper) but no correct step from the ten-step manual procedure is carried out: the loop never contacts a colony, the slide is never smeared or flamed, and no reagent is ever dropped onto anything.
level_3: All core props appear (a colony, an inoculating loop, a glass slide, a flame source, crystal-violet/iodine/alcohol/safranin containers, a microscope, filter paper, an oxidase dropper), and at least five of the ten manual steps occur correctly with the correct tool touching the correct object, but at least two of the remaining steps are missing entirely, are reordered (for example safranin is applied before the alcohol rinse), or are performed with the wrong reagent bottle.
level_4: All ten manual steps occur in the manual's order with correct tool–object pairing at each step (loop to colony, loop to slide, slide through the flame, crystal violet then iodine then alcohol then safranin onto the slide, blotted slide under the microscope, fresh colony onto filter paper, reagent dropper onto filter paper), and the flame pass leaves the slide without visible smoke or scorching, but one non-order flaw remains, such as the microscope eyepiece view staying out of focus, or the oxidase dropper resting on the paper without a visible drop ever falling from it.
level_5: All ten manual steps occur in the manual's exact order with correct tool–object pairing throughout, the flame pass is clean with no smoke or scorch mark on the slide, the microscope eyepiece view is in sharp focus on the smear, and the oxidase dropper is seen releasing a drop that visibly lands and spreads on the filter paper; no step is skipped, reordered, or performed with a substituted tool or reagent.

Scientific and Causal Correctness rubric:
level_1: The stained smear and oxidase paper show no scientifically valid outcome: for example the diplococci render blue-purple (a Gram-positive-looking result) or appear as rods or single cocci rather than paired kidney-bean shapes, and the oxidase-treated filter paper stays white or turns yellow/brown instead of dark purple-black.
level_2: One major scientific error remains uncorrected: either the diplococci are shown as purple/blue-stained cells (the wrong, Gram-positive-looking result for an organism that should read Gram-negative), or the oxidase-treated filter paper turns a color other than purple-black (for example red) or the paper stays completely white despite full, visible reagent contact.
level_3: The diplococci appear pink-to-red, paired, and kidney-bean-shaped (the correct Gram-negative-looking result), and the oxidase paper does eventually turn dark purple-black, but one scientific detail is off: for example the color change on the paper only appears after an implausibly long wait (well over a minute), or a noticeable fraction of the cells in the field still look purple rather than pink, or the diplococci appear as isolated single cocci rather than adjacent pairs.
level_4: Diplococci consistently render pink-to-red, paired, and kidney-bean-shaped, matching the Gram-negative result expected for N. meningitidis, and the oxidase-treated filter paper develops a uniform dark purple-black color within a plausible window (roughly ten seconds to under a minute after contact) with no red, brown, or unchanged-white alternative, but one minor scientific softness remains, such as one or two cells in the field retaining a faint purple tint, or the oxidase color reading slightly more blue than purple-black.
level_5: Every visible diplococcus in the microscope field is uniformly pink-to-red, paired, and kidney-bean-shaped, with no purple- or blue-stained cells and no rods or chains anywhere in the field; the oxidase-treated filter paper develops a uniform deep purple-black color across the entire wetted spot within a plausible window and shows no red, brown, patchy, or unchanged-white result; no other scientific inconsistency appears in either the stain result or the oxidase outcome.

Spatiotemporal Consistency rubric:
level_1: A severe continuity break occurs: for example the slide vanishes between the smearing step and the flame pass and reappears already stained; the loop jumps directly from the agar colony onto the slide with no travel path shown; the microscope eyepiece view cuts straight to the diplococci field with no slide-loading motion ever shown; or the oxidase droplet appears already spread across the filter paper with no drop or fall ever shown.
level_2: Several noticeable continuity breaks occur: more than two abrupt cuts appear between staining steps; the filter paper's position or orientation changes between being picked up and receiving the oxidase drop; the flame appears already lit with no ignition shown; the lighting on the slide or filter paper swings between bright and dim from one shot to the next with no light source ever visibly changing; or the microscope view briefly shows an unrelated field before settling on the diplococci.
level_3: One clear continuity break occurs in an otherwise unbroken sequence: for example a single jump cut appears between the alcohol rinse and the safranin application, or the slide's orientation shifts between the flame pass and the crystal-violet step with no hand visibly moving it, or the oxidase dropper enters the frame already positioned over the paper without its earlier approach ever shown.
level_4: The slide, loop, flame, filter paper, and oxidase dropper each follow a consistent, traceable path through their respective steps (the loop visibly travels from colony to slide to flame to staining area, the filter paper stays flat and unmoved until the drop lands, and the crystal violet, iodine, alcohol, and safranin bottles each appear only during their own step and never resurface out of turn), but one small hiccup remains, such as a brief flicker in the rinse stream or a hand momentarily blocking the slide's corner during fixation.
level_5: The loop's path from colony to slide to flame to reagents to filter paper is continuous and unbroken; the slide never changes position or orientation except by a visible hand motion; the microscope view transitions from the stage to the eyepiece field without a hidden cut; the oxidase droplet visibly forms at the dropper tip, falls, and spreads across the paper in one unbroken motion; and each reagent bottle (crystal violet, iodine, alcohol, safranin) is brought into frame, used, and withdrawn in the correct order, with no bottle reappearing out of sequence.