Domain: Natural Science — Environmental Science
Target concept: Pouring vinegar into the clarified solution of plant ash immediately produces a large number of bubbles, a phenomenon identical to that observed when baking soda reacts with vinegar.

Video generation prompt: A clear plant ash solution is placed in a transparent container. Vinegar is continuously poured into the solution. The lens focuses on the liquid surface and interior during the pouring process, demonstrating the rapid reaction that occurs after contact. The setup is simple, with clear liquid states and continuous pouring, capturing the reaction process in close-up.

Evaluation guide:
(i) Target concept: Acid-carbonate reaction producing CO₂ gas bubbles in aqueous solution.
Minimum mechanism: Aqueous carbonate ion (CO₃²⁻) must be present in solution; weak acid (acetic acid) must be introduced; proton transfer must occur to form unstable carbonic acid (H₂CO₃), which rapidly decomposes to CO₂(g) + H₂O; gas nucleation must occur at interface and sustain in bulk liquid.
(ii)Storyline: [Phase 1] Stable static shot: transparent container holds motionless, clear liquid, with no bubbles. [Phase 2] Vinegar stream enters liquid: immediate bubble nucleation at contact point. [Phase 3] Bubbles rise continuously through interior volume while new bubbles form at entry zone, with no lag, no cessation. [Phase 4] Bubbles reach surface and burst; surface remains agitated but liquid clarity undiminished. [Phase 5] Pouring continues: bubble production sustains at same intensity; all phases unfold in fixed close-up view with no viewpoint change, occlusion, or temporal gap.

Manual:
Experimental Procedure
1. Place a transparent container (e.g., glass beaker) on a stable surface.
2. Fill it with a clarified, colorless solution of plant ash.
3. Pour vinegar continuously into the solution from above, maintaining visible stream contact.
4. Record in close-up, focusing steadily on the liquid surface and interior during pouring.
Observation of Experimental Phenomena
Immediate, abundant, continuous bubble formation appears at the point of vinegar contact and rises through the interior to the surface; bubbles persist as long as pouring continues; liquid remains clear and colorless before, during, and after reaction.
Summary of Experimental Principles
Plant ash solution contains potassium carbonate (K₂CO₃); vinegar contains acetic acid (CH₃COOH); their reaction produces carbon dioxide gas (CO₂), water, and potassium acetate — identical effervescence to baking soda + vinegar.

Prompt Grounding rubric:
level_1: No transparent container is shown; no clarified plant-ash solution is visible; no vinegar being poured; the shot never shows the liquid surface or interior; the scene does not resemble the posted_prompt's pouring setup at all.
level_2: A transparent container OR a clear liquid OR a pouring motion appears, but not together as described: the container is opaque or tinted, the liquid inside looks cloudy or colored rather than a clarified plant-ash solution, vinegar is not visibly streaming into it, or the camera is too wide to show the liquid surface and interior; if pouring happens, it occurs before or after the container is shown rather than during.
level_3: A transparent container holds a visibly clear plant-ash solution; a stream of vinegar is poured into it; the camera holds a close-up that includes at least part of the liquid surface, but the pour is interrupted or restarted rather than continuous, or the camera cuts away from the contact zone before any bubbles could appear, or background clutter partially obscures the container so the liquid's clarity is hard to judge.
level_4: Transparent container with a clearly clear plant-ash solution; vinegar streams into it continuously for the full shot; the camera holds a steady close-up on both the liquid surface and the visible interior throughout the pour; every object and action matches the posted_prompt, apart from one small flaw, such as the pour stream landing slightly off-center, a brief moment well under a second where something briefly blocks the view of the bubble zone, or a short patch of soft focus that still leaves the bubbles visible.
level_5: Transparent container with a visibly clear plant-ash solution; vinegar pours into it in one unbroken stream from start to finish; the camera stays fixed, sharp, and centered on the liquid surface and interior for the entire clip with no blocked view, no cut, and no reframing; the pour stream is visible entering the liquid at every moment; every object, action, camera framing, and order of events matches the posted_prompt exactly.

Scientific and Causal Correctness rubric:
level_1: No bubbles form at any point in the clip; the liquid never changes; nothing about the scene suggests a reaction between the vinegar and the plant-ash solution happened at all.
level_2: Bubbles show up only after a delay of more than a second once the pour has stopped, or they appear scattered and stop-start rather than continuous; the liquid looks cloudy, tinted, or thick, which doesn't match a clarified plant-ash solution reacting with vinegar.
level_3: Bubbles form right where the vinegar first touches the solution and keep rising from within the liquid up to the surface in good numbers; the liquid stays clear throughout, but the bubbles only ever appear right at the surface rather than through the liquid's depth, or bubble production starts and stops rather than staying continuous while pouring continues.
level_4: Bubbles form the instant vinegar contacts the solution and keep forming continuously for as long as the pour continues; bubbles are visible both near the surface and down within the liquid; the liquid stays clear and colorless the whole time with no cloudiness, precipitate, or color shift, apart from one small flaw, such as the bubbling briefly pausing before picking back up, or a thin layer of foam forming at the surface without hiding the bubbles beneath it.
level_5: Bubbles form the instant the vinegar touches the solution and never stop or pause for the entire duration of the pour; they are plentiful, spread through the liquid's depth, and clearly visible rising from within to the surface; the liquid stays fully clear and colorless throughout with no cloudiness, sediment, foam, or color change; the link between vinegar contact and immediate, continuous CO₂ bubble formation is obvious and never interrupted.

Spatiotemporal Consistency rubric:
level_1: The container's position or shape suddenly jumps between shots; the liquid surface skips from one level or state to another with no visible transition connecting them; the pour stream vanishes and reappears without flowing continuously; or the illumination on the liquid switches abruptly from one look to another (for instance a bright highlight on the pour stream disappearing instantly) partway through the pour.
level_2: Several moderate problems appear together: the container rocks or shakes as if unanchored; the pour stream blinks out and back in for more than a moment; the liquid surface ripples in a way that doesn't match where the stream is landing; or the highlight/shadow on the container's curved surface shifts position in a way that doesn't track the pour.
level_3: One small continuity slip occurs: for instance the container's rim looks briefly warped for a moment, the shadow the container casts wobbles slightly out of place for an instant, or the pour stream drifts a touch off its path for a moment, but the container never jumps position, nothing vanishes, and the rest of the scene holds together; the liquid surface otherwise rises and ripples smoothly as vinegar lands in it.
level_4: The pour stream flows in one continuous, physically believable line from source to liquid; the liquid surface dips and ripples smoothly in response to where the stream lands; the container itself never shifts position or shape; the way light glints off the pour stream and the liquid's surface stays believable and doesn't swap direction or intensity out of nowhere, apart from one small flaw, such as a moment of motion blur on the stream that doesn't hide the bubbles or the liquid.
level_5: The container's position and shape stay visibly fixed and unchanged for the whole clip; the pour stream is an unbroken, physically coherent line of liquid from source to surface; the liquid surface and the bubbles beneath it change smoothly and predictably moment to moment; the glint of light on the falling stream and the liquid surface stays convincingly steady in where it comes from and how bright it looks, with no sudden jump; there is no blur, no flicker, and no mismatch in how objects relate to each other in space.