Domain: Natural Science — Atmospheric Science
Target concept: Limewater test: Air is bubbled through a calcium hydroxide solution, forming calcium carbonate.

Video generation prompt: A person exhales breath through a tube into a transparent glass container holding a clear calcium hydroxide solution, with the tube's submerged end reaching below the liquid surface.

Evaluation guide:
(i) Target concept: CO₂ from a person's exhaled breath reacting with aqueous Ca(OH)₂ to precipitate CaCO₃ (the limewater turbidity test).
Minimum mechanism: Exhaled human breath contains roughly 4-5% CO₂, around a hundred times the concentration found in ambient air (~0.04%), which is why breath, rather than ambient air, is used to obtain visible turbidity within a short clip; the Ca(OH)₂ solution must start clear and be freshly prepared; the tube must stay submerged so exhaled CO₂ dissolves directly into the liquid, forming carbonic acid and enabling CaCO₃ nucleation.
(ii) Storyline: Frame 0–2: Static shot showing the clear solution in the upright transparent container with the submerged tube idle and the person poised to exhale. Frame 3–4: The person begins exhaling; first bubbles emerge from the tube tip. Frame 5–7: Bubbles rise continuously; turbidity initiates along the bubble stream's path and spreads through the liquid. Frame 8–10: Full milky-white turbidity is reached and sustained while the person keeps exhaling; the fixed camera keeps the full container and person in view with steady lighting and no occlusion.

Manual:
Experimental Procedure
1. Place a transparent glass container filled with clear calcium hydroxide solution.
2. Insert one end of a flexible tube into the solution until the tip is fully submerged.
3. Have a person place the other end of the tube to their mouth and exhale steadily, blowing breath through the tube into the solution.
Observation of Experimental Phenomena
A cloudy white turbidity appears in the solution soon after exhaled breath begins bubbling through it; the liquid transitions from clear to uniformly milky-white while the person keeps exhaling.
Summary of Experimental Principles
Carbon dioxide in exhaled human breath — roughly a hundred times more concentrated than in ambient air — reacts with dissolved calcium hydroxide to form insoluble calcium carbonate, producing the visible white precipitate and turbidity.

Prompt Grounding rubric:
level_1: None of the required setup elements appear together: no transparent glass container with liquid, no tube, no person, and no visible connection between a person's mouth and one end of a tube leading into the container; the required elements are missing entirely or shown only in unrelated, disconnected shots.
level_2: Some elements appear but the setup is not functional: e.g., a glass container with liquid is shown but no tube reaches into it, or a tube is shown but is not connected to a person's mouth, or the tube's end floats above the liquid surface rather than sitting beneath it; the person, tube, and container do not visibly form one connected setup.
level_3: A transparent glass container holding a clear liquid, a flexible tube with one end submerged below the liquid surface, and a person whose mouth is connected to the tube's other end all appear together in the same shot, with a fixed camera view that keeps the container and tube in frame.
level_4: Everything in the previous level is present, and additionally the tube enters the container at a steady, near-vertical angle, the liquid fills the container to a level clearly visible above the tube's submerged tip, and the person's cheeks or chest visibly move as if exhaling; no unrelated object blocks the view of the container, tube, or person's face.
level_5: Everything in the previous level is present, and additionally the tube's tip stays fully submerged for the entire clip, the container stays upright and does not shift position, the person's exhaling motion is visible and continues rather than appearing as a single static pose, and no synthetic distortion changes the shape or identity of the person, tube, or container at any point.

Scientific and Causal Correctness rubric:
level_1: No turbidity or cloudiness ever appears in the solution, regardless of whether the person is exhaling into the tube; the liquid stays visibly clear from start to end with no observable link between the bubbling and the liquid's appearance.
level_2: The liquid develops a color other than white (for example yellow or brown) or a cloudiness appears before the person starts exhaling or lingers after they visibly stop, so the cloudiness is not tied to the timing of the bubbling through the tube.
level_3: A milky-white cloudiness appears in the solution specifically once the person's exhaled bubbles begin rising from the submerged tube tip; the solution is visibly clear in the moments before the bubbling starts, and the cloudiness spreads into the body of the liquid rather than sitting only as a thin film at the surface.
level_4: Everything in the previous level holds, and additionally the milky cloudiness visibly thickens and spreads further through the liquid the longer the person keeps exhaling, with no clearing or settling back to transparency while bubbling continues, and no color other than white ever appears.
level_5: Everything in the previous level holds, and additionally by the end of the clip the entire volume of liquid looks uniformly milky-white rather than streaked only along the bubble's rising path, the suspension has the fine, even look of a chalky precipitate rather than clumps or floating flakes, and no clear patches of liquid remain once the milky state is reached.

Spatiotemporal Consistency rubric:
level_1: A severe break in continuity occurs: the container, the tube, or the person's head is missing from the shot for part of the clip and then reappears in a different spot with no camera movement to account for it; the liquid's clarity or fill level changes suddenly between frames without any bubbles having risen through it in between; the container's outline or the tube's path looks broken or reassembled, as though stitched together from mismatched shots; or the lighting suddenly flips between bright and dim from one frame to the next with no change in the room or the person's exhaling to explain it.
level_2: The submerged end of the tube appears at a different depth or bent into a different shape from one moment to the next even though the person's hand and mouth show no matching movement; the stream of bubbles cuts out and restarts inconsistently without the person visibly pausing their exhale; the refracted image of the tube seen through the curved container wall does not line up with where the tube actually sits outside the glass.
level_3: The person, the tube, and the container each keep one consistent position and orientation across the clip, allowing for the person's small natural movement while exhaling; the tube's submerged depth in the liquid does not change; the refracted image of the tube seen through the curved glass wall stays aligned with the tube's true position outside the container.
level_4: Everything in the previous level holds, and additionally the bubble stream rising from the tube tip flows at a steady, uninterrupted rate without freezing or jumping in count between frames, and the milky-cloudy region expands outward from the bubble path in a continuous gradient rather than appearing as disconnected patches.
level_5: Everything in the previous level holds, and additionally the shift from clear to milky-white liquid stays optically coherent when viewed through the curved glass: the refracted view of the tube and rising bubbles fades gradually as the surrounding liquid turns opaque, instead of abruptly vanishing, doubling, or being replaced by a mismatched reflection; no part of the person, tube, or container flickers or changes shape between frames.