Domain: Natural Science — Physics
Target concept: Saline Concentration and Boiling Point

Video generation prompt: Two identical alcohol lamps and beakers are placed side by side on the table, with the beakers positioned above the ignited alcohol lamps; the left beaker contains a certain amount of water, while the right beaker contains an equal volume of saturated saltwater solution; heat the beakers until the solutions boil, and observe the order in which the left and right beakers begin to boil.

Evaluation guide:
(i) Target concept: Boiling point elevation due to solute concentration (colligative property)
Minimum mechanism: Pure water and saturated saltwater must be heated identically (same heat source intensity, same exposure time, same container geometry, same ambient pressure); saltwater must be truly saturated (visually indistinguishable from pure water except for delayed boiling); no evaporation or splashing alters relative concentrations during heating.
(ii)Storyline: Frame 1–2: Two lit alcohol lamps visible, flames steady; two beakers positioned directly above, side-by-side, both containing transparent liquids. Frame 3–5: First sustained bubbling appears exclusively in left beaker (≥2 surface-breaking bubbles, continuous for ≥3 frames). Frame 6–8: Left beaker bubbling continues; right beaker remains quiescent (no bubbling, no surface agitation beyond thermal shimmer). Frame 9–10: First sustained bubbling appears in right beaker, only after left bubbling is already established. Perspective: Fixed frontal view, full beaker height visible, no occlusion, consistent lighting from below via flames.

Manual:
Experimental Procedure
1. Place two identical alcohol lamps side-by-side on a table.
2. Light both lamps.
3. Place two identical beakers side-by-side directly above the flames: left beaker filled with water, right beaker filled with saturated saltwater (equal volume).
4. Observe boiling onset sequence.
Observation of Experimental Phenomena
Water in left beaker begins boiling (sustained surface bubbling) before saturated saltwater in right beaker begins boiling.
Summary of Experimental Principles
Dissolved salt raises boiling point of water; saturated saltwater requires higher temperature to boil than pure water, so it boils later under identical heating conditions.

Prompt Grounding rubric:
level_1: Fewer than two alcohol lamps or fewer than two beakers appear anywhere in the shot, or neither lamp is ever lit.
level_2: Two lamps and two beakers are all present and at least one lamp is lit, but they are not arranged side by side (e.g., stacked, diagonal, or one pair hidden behind the other), only one of the two lamps is lit, or one of the two beakers has no visible liquid in it.
level_3: Two identical, lit alcohol lamps sit side by side on the table with a beaker positioned directly above each one, also side by side; the left beaker holds a visible liquid and the right beaker holds a visible liquid, and both liquids fill comparable amounts of their beakers.
level_4: All of score 3, plus both liquids look transparent and colorless, matching the fact that saturated saltwater looks the same as plain water to the eye (there is no dye or added color that would let a viewer tell which beaker is which just by looking at the liquid), and neither beaker is tilted, cracked, or knocked out of place.
level_5: All of score 4, plus the side-by-side arrangement of both lamp-beaker pairs stays fully visible for the whole video, both flames stay lit throughout, both beakers stay upright and still, and the camera keeps a level frontal framing that shows the full height of both beakers and both flames without cropping or zooming.

Scientific and Causal Correctness rubric:
level_1: Neither beaker ever shows boiling, both beakers appear to start boiling at the same time, the right (saltwater) beaker boils before the left, or the right beaker boils vigorously while the left only shows a few bubbles.
level_2: Only one of the two beakers ever shows real boiling, what looks like boiling in either beaker is ambiguous (steam or mist without sustained bubbling), or the left beaker's bubbling starts so close in time to the right beaker's that a viewer cannot confidently say which one boiled first.
level_3: Continuous, multi-bubble surface-breaking boiling starts in the left beaker first, and only later does the same kind of boiling start in the right beaker, with both lamps still lit and both beakers still in place when this happens.
level_4: All of score 3, plus there is a clearly visible stretch of the video where the left beaker is boiling and the right beaker shows no bubbling at all yet, making the gap between the two onsets unambiguous rather than a near-tie.
level_5: All of score 4, plus the left beaker's boiling is sustained (multiple bubbles breaking the surface over several consecutive moments, not just one or two), the right beaker's boiling only begins once the left beaker's boiling is already well underway, and nothing on screen (steam wisps, reflections, dust) could be mistaken for bubbling in either beaker.

Spatiotemporal Consistency rubric:
level_1: A lamp or beaker disappears and reappears between frames, a flame vanishes and comes back fully formed with no transition, the lighting or shadows shift abruptly (e.g., a shadow vanishes and then reappears) with no visible cause, the liquid level in a beaker jumps with no cause, or a beaker cracks or shatters mid-video with no visible cause.
level_2: A flame's height changes erratically frame to frame with no smooth build-up or die-down, a beaker's position shifts or rotates with no visible cause, or a liquid surface wobbles in a way real liquid would not (e.g., bouncing like gelatin).
level_3: Both flames flicker only with the small, natural variation real flames show; both liquid surfaces show a gentle, continuous simmer or undulation rather than sudden jumps; both beakers stay in the same place and orientation; no abrupt cuts or warping occur anywhere in the video.
level_4: All of score 3, plus both flames keep a plausible, roughly steady shape across the whole video, the liquid surfaces move continuously without freezing or stuttering, and the camera framing itself does not drift or shift as if the camera were moving.
level_5: All of score 4, plus each flame's shape, brightness, and position change smoothly from frame to frame with no strobing or sudden jitter, each liquid's surface motion looks physically plausible with no unnatural standing-wave patterns, and neither beaker's overall brightness spikes or drops in a way unrelated to the flame beneath it.