Domain: Natural Science — Chemistry
Target concept: Calcium chloride dissolves in ice water (exothermic).

Video generation prompt: A transparent glass beaker containing distilled water is placed in a tray filled with ice; solid calcium chloride particles are added and gently stirred.

Evaluation guide:
(i) Target concept: Exothermic dissolution of calcium chloride in water, observed primarily through the solution's own thermal behavior at the point of contact with the solid, with the surrounding ice serving as a secondary, non-definitive cue.
Minimum mechanism: Dissolution occurs in the aqueous phase and releases heat into the solution; because an endothermic or non-reacting solute would leave the ice looking the same, 'the ice stays unmelted' cannot, on its own, prove exothermicity; a more specific cue is that any thinning of ice is confined to a thin margin in direct contact with the beaker wall (heat conducting outward through the glass), while ice away from the beaker stays unaffected, and the ice tray as a whole should not show widespread or bulk melting.
(ii)Storyline: Frame 1–2: Static shot showing beaker-in-tray setup with visible ice and clear water. Frame 3–4: Calcium chloride particles descend into beaker and contact water surface. Frame 5–7: Immediate localized cloudiness at contact zone; particles visibly reduce in size while submerged; no expansion or bubbling. Frame 8–10: Turbidity dissipates uniformly; ice away from the beaker wall stays unchanged in shape, position, and opacity; at most a thin margin of ice touching the beaker may thin slightly; no condensation forms on the beaker's exterior; stirring continues smoothly to completion. Perspective: Fixed frontal view, centered on beaker interior; no occlusion; full beaker and upper ice margin always visible.

Manual:
Experimental Procedure
1. Place a transparent glass beaker containing distilled water into a tray filled with ice.
2. Add solid calcium chloride particles to the water.
3. Gently stir with a glass rod.
Observation of Experimental Phenomena
- Calcium chloride dissolves rapidly in water with no color change.
- Localized transient turbidity appears at particle contact points, then clears.
- Ice away from the beaker wall stays physically intact and unmelted; at most a thin margin of ice directly touching the beaker may thin slightly as heat conducts outward through the glass.
Summary of Experimental Principles
Calcium chloride dissolving in water is exothermic: the ions release more hydration energy than is needed to break the ionic lattice, so the solution's temperature rises. Because an endothermic or non-reacting solute dissolving nearby would leave the surrounding ice looking the same, 'the ice stays unmelted' by itself does not prove the process is exothermic — the more specific evidence is the solution's own warming, which can conduct through the beaker wall to thin the ice immediately touching it, rather than causing the ice tray as a whole to melt.

Prompt Grounding rubric:
level_1: No beaker is visible; no ice-filled tray is visible; no solid calcium chloride particles are shown; no stirring action is depicted; none of the three core objects (beaker, ice tray, CaCl₂ solid) appear in recognizable form.
level_2: At least one core object appears (a transparent container, or ice, or white granular solid), but at least two are missing or misidentified: for example a powder is shown but not placed near the water, or stirring motion appears with no visible rod or beaker.
level_3: All three core objects are present and correctly identified: a transparent glass beaker containing liquid, a tray filled with visible ice chunks (solid and crystalline, not mist or vapor), and solid white granular calcium chloride particles that have not yet dissolved at the start; a stirring rod or spoon is visibly used inside the beaker; the sequence shows the beaker placed in the tray, then the particles added, then stirring.
level_4: Everything in score 3 holds, and the spatial relationships are correct: the beaker sits inside the ice-filled tray (not beside it or floating above it); the calcium chloride particles are added directly into the beaker's water, not onto the ice or outside the beaker; stirring only happens after the particles are added and stays confined to the beaker; nothing extraneous (labels, a hand with no visible tool, unrelated chemicals) blocks or replaces the core objects.
level_5: Everything in score 4 holds, and every object keeps a consistent look throughout: the beaker stays transparent and undistorted; the ice keeps its crystalline, opaque-white look without melting artifacts before the particles are added; the calcium chloride particles stay dry and granular until they touch the water; the stirring rod stays visible and in motion for the whole stirring phase; nothing flickers, disappears, or changes type mid-sequence.

Scientific and Causal Correctness rubric:
level_1: No state change is observed; the liquid stays visually unchanged; the ice shows no interaction with anything added; the calcium chloride particles vanish or sit inert on the surface; no thermal effect is implied (no steam, condensation, or fogging); there is no causal link between adding the particles and any phenomenon.
level_2: A single phenomenon appears but contradicts chemistry: for example the ice visibly melts before the calcium chloride is added; the liquid turns colored; particles dissolve instantly on air exposure before touching water; the beaker fogs before addition; or the beaker exterior frosts over, which would instead suggest an endothermic (cooling) process rather than an exothermic one.
level_3: The causal sequence is visually verifiable: calcium chloride particles are added to the water, immediate localized cloudiness or transient turbidity appears at the point of contact, and the ice in the tray shows no widespread melting during or immediately after addition; this is consistent with, though not by itself proof of, an exothermic dissolution where the released heat stays mostly in the solution; no color change, gas evolution, or precipitation occurs.
level_4: Everything in score 3 holds, and the dissolution shows continuity: turbidity appears only after the particles contact the water and spreads gradually outward from the contact point; the particles visibly shrink only while submerged; there is no re-solidification or phase separation; ice away from the beaker's wall stays physically unchanged throughout, and if any ice touching the beaker thins slightly, that thinning stays local to the contact margin rather than spreading through the tray.
level_5: Everything in score 4 holds, with no remaining scientific inconsistency: the turbidity clears fully or partially without settling into visible layers; there is no bubbling or surface agitation beyond what the gentle stirring itself would cause; the beaker's exterior shows no condensation or frost forming; and the whole sequence proceeds in one direction only (addition, contact, localized turbidity, then gradual clearing), never in reverse or all at once.

Spatiotemporal Consistency rubric:
level_1: The beaker jumps to a different spot in the tray with no motion shown; the ice cubes vanish and reappear; a calcium chloride particle appears already inside the liquid with no path shown for how it got there; the stirring rod appears to pass straight through the beaker wall; or the lighting in the frame changes abruptly as if two different shots were spliced together.
level_2: At least two of the following occur: the beaker's transparency or shape changes between frames; the ice cubes shrink or grow inconsistently from one frame to the next; the stirring motion jerks, stops, or restarts without any motion blur; the shadow cast by the beaker or ice swaps to the opposite side with no light source moving; or background objects shift or warp with no camera movement to explain it.
level_3: The beaker stays fixed in the ice tray; the ice cubes stay in place and keep their shape aside from natural settling; the calcium chloride particles fall and sink along a physically plausible path; the stirring rod moves in a continuous, smooth arc inside the beaker; nothing flickers, tears, or distorts.
level_4: Everything in score 3 holds, and the particles fall at a steady downward rate without floating or hovering; the stirring keeps a consistent direction and speed with no sudden reversal or freeze; the stirring rod never passes through the beaker wall or bottom; the shadow cast by the beaker and ice tray stays in the same place relative to the static setup.
level_5: Everything in score 4 holds, and there is no stutter from duplicated or dropped frames; no ghosting or motion blur obscures any object's identity; the camera framing never jumps or shows a parallax shift; the relative scale and perspective of the beaker, ice, and stirring rod stay the same; every object's edges stay crisp and unbroken across the whole video.