Domain: Natural Science — Physics
Target concept: Conductivity Comparison between Salt Water and Distilled Water (Using a Small Motor)

Video generation prompt: A circuit powered by a battery and connected through a small motor links metal electrodes placed in two transparent beakers positioned side by side: the left one contains saltwater, and the right one contains distilled water, with current passing through each beaker separately.

Evaluation guide:
(i) Target concept: Electrical conductivity depends on mobile charge carriers in solution; ionic solutions conduct, pure molecular liquids do not.
Minimum mechanism: Electrodes must be in direct contact with liquid; circuit must be series-connected through liquid; bubble formation requires sustained current above decomposition voltage; motor rotation requires sufficient current to overcome static friction and drive load.
(ii)Storyline: Frame 0–2s: Static wide shot showing two beakers side-by-side, labeled left/right; electrodes inserted, liquids filled, battery and motor placed nearby with loose wires. Frame 2–4s: Wires connected to left beaker electrodes; motor begins rotating smoothly; simultaneous appearance of discrete bubbles at both left electrodes. Frame 4–6s: Wires disconnected from left and reconnected to right beaker; motor stops completely before reconnection; no bubbles appear during or after right-beaker connection. Frame 6–10s: Sustained stillness of motor and right beaker; persistent rotation and bubbling on left (if looped or held); viewpoint remains fixed frontal, full beaker height in frame, no occlusion of electrode–liquid interfaces.

Manual:
Experimental Procedure
1. Place two identical transparent beakers side-by-side on a flat surface.
2. Fill left beaker with saltwater, right beaker with distilled water.
3. Insert identical metal electrodes into each beaker, fully submerged.
4. Connect battery to small motor, then connect motor output wires to electrodes in left beaker only — observe motor rotation and bubbles at electrodes.
5. Disconnect left, reconnect same wires to electrodes in right beaker — observe motor remains still and no bubbles form.
Observation of Experimental Phenomena
- Motor rotates continuously only when connected to saltwater beaker.
- Steady stream of small gas bubbles rises from both electrodes in saltwater beaker.
- Motor does not rotate and zero bubbles appear in distilled water beaker.
Summary of Experimental Principles
Saltwater contains dissolved ions (Na⁺, Cl⁻) that carry electric current, completing the circuit and enabling electrolysis (producing H₂ and O₂ bubbles) and motor operation. Distilled water lacks sufficient ions, so it cannot conduct appreciable current — the circuit remains open, no electrolysis occurs, and motor stays off.

Prompt Grounding rubric:
level_1: No battery, no small motor, no two transparent beakers, no metal electrodes, or no liquid visible in either beaker; the scene bears no resemblance to the described circuit-and-beakers setup.
level_2: At least one beaker with liquid and electrodes is visible, and a battery is present, but the two beakers are not placed next to each other (e.g., stacked, overlapping, or only one beaker shown), or the small motor is missing or not wired into the circuit, or the electrodes are not actually inserted into the liquids.
level_3: Two transparent beakers sit side by side; a battery and a small motor are both present and connected by wires; metal electrodes are inserted into each beaker; both beakers contain a visible liquid; every object named in the prompt is present and arranged as described, but the left and right liquids look identical (no visible difference in clarity or color) or the electrode contact with the liquid is unclear.
level_4: All of score 3 holds, and every object from the prompt is clearly and correctly placed: two transparent beakers side by side, a battery, a small motor, connecting wires, and metal electrodes fully submerged in each beaker; the left beaker's liquid is clearly visible around its electrode, and the right beaker's liquid is equally clearly visible around its electrode, with nothing missing, misplaced, or structurally broken.
level_5: All of score 4 holds, and the beakers are unambiguously identifiable by position (the left is clearly established as saltwater and the right as distilled water); the wiring visibly runs in a complete series loop from battery through motor to the electrodes of whichever beaker is connected; the side-by-side layout stays centered, stable, and fully in frame for the entire clip; no particular motor behavior or bubble outcome is required at this level, only that the full setup remains intact and legible throughout.

Scientific and Causal Correctness rubric:
level_1: No effect of the current is visible at all (the motor stays still, no bubbles form, and both beakers look identical and static), or, contradicting the science, the motor spins the same way regardless of which beaker is wired in.
level_2: The motor spins, but it behaves identically for both beakers (same speed and duration), or bubbles form equally in both beakers, or the motor spins only while the distilled-water beaker is wired in; any of these contradicts the fact that saltwater conducts far better than distilled water.
level_3: The motor spins only while the saltwater (left) beaker is wired into the circuit and stays still while the distilled-water (right) beaker is wired in, or it spins in both cases but behaves noticeably differently between them (e.g., it starts and then stops only for the right beaker), but there is no visible sign of the underlying conduction difference at the electrodes themselves, such as bubbles on the left or a visible contrast in electrode activity between the two beakers.
level_4: The motor spins continuously only when the saltwater beaker is wired in and stays completely still when the distilled-water beaker is wired in; small, steady gas bubbles rise from both electrodes in the saltwater beaker; no bubbles appear at any point in the distilled-water beaker; the visible bubbling and motor behavior together match the expected conductivity difference.
level_5: The motor spins only when the saltwater beaker is wired in, starting smoothly and running steadily, with zero rotation while the distilled-water beaker is wired in; the saltwater beaker shows a continuous, steady stream of bubbles from both electrodes; the distilled-water beaker shows no bubbles, no shimmer at the electrode surface, and no disturbance of the liquid surface at any point; this contrast holds for the entire visible duration, with no late bubbles appearing on the right or the left's bubbling stopping early.

Spatiotemporal Consistency rubric:
level_1: Severe spatiotemporal rupture: one or both beakers instantly relocate to a different spot on the table between frames with no motion connecting the two positions; the motor or wiring vanishes and reappears without anyone touching it; an electrode detaches from its beaker and reattaches with no visible hand or action causing it; the camera view jumps or cuts to a different angle without any transition; or the lighting changes abruptly between shots with no apparent cause (e.g., shadows suddenly reverse direction or the scene instantly brightens or darkens).
level_2: Moderate rupture: one beaker's position shifts noticeably between shots without anything moving it; an electrode's depth in the liquid changes without any hand adjusting it; the motor starts spinning, stops, and starts again with no visible change in which beaker is wired in to explain it; the background behind the beakers shifts or resets partway through the clip.
level_3: Minor but noticeable flaws: a beaker jitters slightly in place, the motor's rotation flickers for a frame or two, or an electrode's surface shows an inconsistent highlight, but the side-by-side layout of the two beakers, the presence of all objects, and the sequence of wiring one beaker then the other remain clear and easy to follow throughout.
level_4: All of score 3 holds, and additionally: both beakers stay fixed in their side-by-side spots, the electrodes remain fully inserted and undisturbed, and the motor's rotation (when active) is smooth with no stutter or momentary reversal; only one small flaw remains, such as a single-frame flicker in a wire's visibility or a brief odd glint on one beaker's glass.
level_5: No spatiotemporal flaws are visible anywhere in the clip: both beakers stay perfectly still and aligned side by side; the electrodes stay motionless and fully submerged the whole time; the motor's rotation, when it happens, holds a constant visible speed with no skipped frames or sudden speed changes; the glass beakers' outlines and the wires connecting them stay geometrically consistent from frame to frame, with no jump, warp, or gap in the connections at any point.