Domain: Natural Science — Chemistry
Target concept: Salt dissolves in water, enabling electrical conductivity between the electrodes.

Video generation prompt: Two transparent beakers are placed side by side, each containing identical metal electrodes, a battery, and a light bulb in a circuit; one beaker contains pure water, while the other contains water with dissolved salt, and the circuits are then simultaneously closed.

Evaluation guide:
(i) Target concept: Electrical conductivity in aqueous solutions depends on presence of mobile ions.
Minimum mechanism: Dissolved NaCl must dissociate into Na⁺ and Cl⁻ ions; pure water must have negligible ion concentration (<10⁻⁷ M H⁺/OH⁻) under standard conditions; circuit must be series-connected with bulb as current indicator; no redox reactions or electrolysis products visible at this scale/timescale.
(ii)Storyline: Frame 1–2: Static wide shot showing two side-by-side transparent beakers, each with submerged metal electrodes, wired to separate identical battery–bulb circuits; one beaker has label “Pure Water”, other “Salt Water” (or salt crystals visible beside second beaker pre-closure). Frame 3: Simultaneous closure action (e.g., two fingers flipping switches or connecting wires). Frame 4–10: Stable shot holding position; bulb in salt water beaker turns ON and remains steadily lit; bulb in pure water beaker remains OFF; no secondary phenomena (bubbling, heating, color change); all objects remain fully visible, front-lit, and in fixed spatial configuration; viewpoint is fixed frontal mid-shot, no zoom/pan.

Manual:
Experimental Procedure
1. Place two identical transparent beakers side-by-side on a flat surface.
2. Insert identical metal electrodes into each beaker, fully submerged.
3. Connect each electrode pair to a separate identical circuit: battery → electrode → light bulb → electrode.
4. Ensure one beaker contains only pure water; the other contains water with dissolved table salt.
5. Simultaneously close both circuits.
Observation of Experimental Phenomena
The light bulb in the salt water circuit illuminates; the bulb in the pure water circuit remains unlit.
Summary of Experimental Principles
Salt dissolves in water to form mobile ions, enabling electrical conductivity between the electrodes. Pure water lacks sufficient ions to complete the circuit, so no current flows and the bulb stays off.

Prompt Grounding rubric:
level_1: Neither of the two transparent beakers is shown; no metal electrodes appear in either beaker; no battery or light bulb is visible in either circuit; the two beakers are not placed together for a side-by-side comparison; no circuit-closing action (e.g., a switch flip or wire connection) is depicted.
level_2: Two containers appear, but at least one is opaque or not beaker-shaped; electrodes appear in at least one beaker but are not identical in both (e.g., different metal, length, or shape); a battery or bulb is visible but is not wired into a complete loop with its beaker's electrodes; the two containers sit apart or at an angle rather than directly next to each other.
level_3: Two transparent beakers sit side-by-side; identical metal electrodes are inserted into each; a battery and light bulb are present and wired into a circuit with the electrodes in each beaker; both circuits are closed at the same visual moment (e.g., both switches flip or both wires connect together); however, nothing distinguishes which beaker holds pure water and which holds the salt solution (no label, no visible salt crystals, no other cue).
level_4: All elements from 3-score are present and correctly arranged: two transparent beakers side-by-side, identical metal electrodes in both, a battery and bulb fully wired into two separate circuits, and simultaneous circuit closure clearly shown; one beaker also carries a clear visual cue distinguishing it as the salt-water beaker (e.g., a legible label such as "Salt Water"/"Pure Water," or a few undissolved salt crystals visible near it before closure — dissolution itself need not be shown); neither beaker nor electrode jumps position, duplicates, or changes shape between shots.
level_5: All elements from 4-score are present, and additionally: the two beakers match in size and orientation; the electrodes match in shape, color, and how deep they sit in the liquid; the batteries and bulbs match in appearance and wiring layout; the closure action is synchronous and unambiguous (e.g., two matching switches flip down in the same moment, or two hands connect wires at mirrored positions); no stray objects, occlusions, or visual clutter appear in frame; any label used is consistent, legible, and unobtrusive; the camera holds a fixed viewpoint and steady framing throughout.

Scientific and Causal Correctness rubric:
level_1: No observable difference in bulb illumination between beakers; both bulbs are lit or both unlit regardless of liquid content; electrodes submerged in air or outside liquid; liquid state is incorrect (e.g., solid salt shown inside beaker *during* circuit operation without dissolution context).
level_2: Bulb illumination state is inconsistent with conductivity principle: e.g., bulb lit in pure water beaker and unlit in salt water beaker; or both bulbs lit despite pure water beaker having no conductive solute; or illumination appears before circuit closure.
level_3: Bulb in salt water beaker is lit and bulb in pure water beaker is unlit; illumination occurs only *after* circuit closure; electrodes remain fully submerged in liquid during illumination; liquid in both beakers appears as clear liquid (no opacity, turbidity, or precipitate that contradicts “dissolved salt” or “pure water”); no contradictory state changes (e.g., salt crystals dissolving *during* illumination sequence).
level_4: All conditions from 3-score are satisfied, and additionally: no visual artifact implies false causality (e.g., bulb flickering in pure water beaker, or delayed lighting in salt beaker suggesting resistance rather than absence of conduction); liquid appearance remains stable (no bubbling, gas evolution, heating, or color shift inconsistent with room-temperature NaCl solution and DI water); electrode surfaces show no corrosion, plating, or discoloration inconsistent with brief DC current in dilute electrolyte.
level_5: All conditions from 4-score are satisfied, and additionally: illumination intensity difference is *not depicted* (since brightness is not assessable without calibrated measurement, and subject knowledge only requires binary on/off distinction); no motion blur obscures bulb state; both bulbs show identical filament structure and orientation; no reflection, glare, or lighting artifact creates false impression of illumination/unillumination; electrode–liquid interface is sharply visible and fully submerged for entire duration.

Spatiotemporal Consistency rubric:
level_1: Severe spatiotemporal violations: one or both transparent beakers change position or vanish and reappear elsewhere between frames; an electrode's position or orientation inside its beaker changes discontinuously; a bulb or battery disappears and reappears; the shadow cast by a beaker or electrode swings to the opposite side with no light source or camera movement to explain it; a circuit wire visibly snaps apart or reconnects without any hand or switch action causing it.
level_2: One beaker or electrode undergoes unnatural scaling or warping; an electrode partially vanishes behind a beaker wall then reappears fully; a bulb flickers off and on without any switch action; the background behind the beakers changes texture or color between frames for no lighting-related reason; a wire's end is shown adjacent to an electrode without actually making contact.
level_3: All objects maintain consistent spatial relationships: both beakers remain side-by-side in fixed relative position; each electrode stays inserted at a constant depth in its beaker; the bulbs and batteries retain their fixed mounting and orientation; the circuit wires remain taut and continuously connected in the loop from battery to electrode to bulb to electrode to battery on each side; no object flickers, vanishes, or warps; the highlight on the glass beakers and the shadow cast by each electrode stay in the same position and brightness across the sequence.
level_4: All conditions from 3-score are satisfied, and additionally: motion (e.g., a switch flip or hand movement) is smooth and physically plausible with no jerky acceleration or deceleration; no tearing or shearing distorts any object between frames; each electrode's immersion depth stays constant; the liquid surface in both beakers stays still, with no ripples or waves that would be inconsistent with an undisturbed demonstration; the camera does not jump or refocus mid-sequence.
level_5: All conditions from 4-score are satisfied, and additionally: the camera framing stays visibly steady with no shake or drift; once lit, the bulb's brightness does not pulse, flicker, or strobe; fast actions such as a hand flipping a switch or connecting a wire render as smooth, continuous motion rather than a garbled or stuttering blur; all motion follows its natural path (e.g., a switch shows its full travel arc rather than jumping instantly from off to on); the liquid meniscus in each beaker and the electrodes' reflections stay geometrically consistent across frames.