Domain: Engineering — Energy Engineering
Target concept: Clean Energy (Hydrogen Energy): Hydrogen combustion produces only water droplets.

Video generation prompt: A small hydrogen combustion device on the table ignites hydrogen, and a cold, dry beaker is placed above the flame to observe the changes on the inner wall of the beaker after hydrogen combustion.

Evaluation guide:
(i) Target concept: Condensation of water vapor (the sole product of pure hydrogen combustion) onto a thermally conductive, sub-dew-point surface.
Minimum mechanism: Hydrogen must combust stoichiometrically in air to yield only H₂O(g); beaker surface temperature must be below local dew point of resulting vapor-air mixture; beaker must be initially dry and non-porous to prevent false condensation signals.
(ii)Storyline: [Phase 1: Baseline] Cold, dry beaker shown empty and upright; flame off; inner wall clear and featureless. [Phase 2: Ignition] Device ignites → pale-blue flame appears; no soot or color shift. [Phase 3: Placement] Beaker moves into frame and settles motionless above flame; no lateral/rotational correction. [Phase 4: Condensation Onset] Droplets appear *only* on inner wall, beginning near top center, increasing in count/size synchronously with flame duration. [Phase 5: Steady State] Droplets remain discrete, spherical, and confined to inner wall; flame unchanged; no secondary phenomena (fog, runoff, rim wetting). Perspective: Fixed frontal-medium shot; beaker and flame fully in frame; no occlusion; inner wall fully visible throughout.

Manual:
1. Ignite a small tabletop hydrogen combustion device to produce a steady pale-blue flame.
2. Hold a cold, dry beaker upright and motionless directly above the flame.
3. Observe the inner wall of the beaker: discrete water droplets form and accumulate there.
Observation: Only spherical water droplets appear exclusively on the inner wall of the beaker during combustion; no soot, smoke, or discoloration occurs.
Principle: Hydrogen combustion produces only water vapor, which condenses into visible droplets upon contact with the cold, dry beaker surface.

Prompt Grounding rubric:
level_1: No hydrogen combustion device, no flame of any kind, and no beaker appear anywhere in the scene; nothing resembling a beaker being placed above a flame is shown.
level_2: A device or a beaker appears, but not both; the flame shown is clearly not a pale hydrogen flame (for example, a yellow or orange flame with a visible sooty tip); the beaker never ends up positioned above any flame; or the beaker is shown above the flame before the flame is even ignited.
level_3: A small tabletop device with a visible gas inlet ignites into a sustained pale-blue flame; a beaker is placed directly above that flame and held there; the device, the flame, and the beaker positioned above it are all visible together in the same shot.
level_4: All of score 3, plus the beaker is upright, transparent, and visibly held still above the flame long enough for its inner wall to be observed; the device shows hydrogen-specific cues, such as a labeled gas line and no soot-producing burner nozzle; nothing blocks the view of the beaker or the flame beneath it.
level_5: All of score 4, plus the beaker's inner wall is visibly clear and dry before the flame is lit, with no droplets or haze present beforehand; the flame stays pale blue throughout, with no orange or yellow tinge at its tip; the device clearly reads as a small tabletop unit rather than a floor-standing or built-in lab apparatus; the beaker holds its exact position above the flame for the entire sequence, without shifting sideways, tilting, or being repositioned.

Scientific and Causal Correctness rubric:
level_1: No droplets ever form anywhere on the beaker's inner wall: its surface stays exactly as clear and dry as it started, even though the flame has been burning for some time.
level_2: Droplets or haze appear on the beaker's outer wall or base rather than the inner wall; or droplets are already present before the flame is lit, or remain after the flame is put out; or the inner wall shows only a single uniform haze rather than separately distinguishable droplets.
level_3: Distinct, rounded droplets appear on the inner wall specifically while the flame is burning, starting from a wall that was clear and dry beforehand; no soot or discoloration appears anywhere on the beaker; the droplets increase in number or size the longer the flame continues to burn.
level_4: All of score 3, plus the droplets stay confined to the inner wall only, with none appearing on the rim, the outside, or the base of the beaker; droplet formation begins only after the beaker has been over the flame for a short while rather than the instant it is placed there, consistent with vapor needing time to reach and cool on the glass; the inner wall shows no trace of moisture at the very start.
level_5: All of score 4, plus the droplets stay separate and rounded rather than merging into streaks or a continuous film, appearing mostly in the upper part of the inner wall where rising vapor first reaches the cooler glass; no droplet ever appears on the rim or outer surface; the droplet pattern builds up gradually over the course of the flame rather than appearing all at once in a single jump.

Spatiotemporal Consistency rubric:
level_1: The flame or the beaker appears to jump to a different position between shots, or either one seems to blink out of view and reappear moments later; the scene's overall brightness changes suddenly with no visible cause, as if two different lighting setups were spliced together.
level_2: The flame's height or brightness swings wildly and unnaturally from one moment to the next; the beaker rocks or slides sideways by more than about a third of its own width; the shadow cast by the beaker or device points in different directions at different times with no explanation; a visible cut interrupts the shot between the beaker being placed and the flame being observed.
level_3: Only slight handheld-camera-style shake is visible, with no object shifting by more than about a fifth of the beaker's width; the flame keeps a steady vertical orientation; the shadow's direction and softness stay the same across the sequence; the beaker's position drifts by less than about a tenth of its height, vertically or laterally, if at all; and neither the beaker nor the flame disappears at any point.
level_4: The beaker stays in the same position, angle, and size for the whole sequence; the flame's height and shape change only gradually and mildly (varying by no more than about 10%), never spiking or guttering suddenly; shadows and highlights shift only in step with the flame's own gentle variation rather than on their own; no frame shows tearing, warping, or a sudden change in perspective.
level_5: All of score 4, plus the flame holds a steady shape from frame to frame with no visible flicker or wobble; the beaker shows no visible shake or blur beyond what its stillness would naturally produce; reflections and highlights on the beaker's glass shift smoothly and plausibly as the flame varies gently; no frame shows strobing or stutter in the flame's or beaker's motion.