Domain: Engineering — Materials Science & Engineering
Target concept: Copper wire/Aluminum wire lights up, plastic wire does not light up.

Video generation prompt: A white background, a broken LED circuit loop. First, the circuit is bridged with copper wire, then with plastic thread, observing the LED light.

Evaluation guide:
(i) Target concept: Electrical conductivity as a material-dependent property determining circuit completion.
Minimum mechanism: Closed-loop current path required for LED operation; metallic conductors (e.g., copper) permit electron flow; polymeric insulators (e.g., plastic thread) prohibit electron flow under low-voltage DC conditions.
(ii)Storyline: Frame opens on static white-background shot showing intact but open-circuit LED assembly with two exposed terminals. First phase: copper wire enters frame and makes simultaneous, stable contact across both terminals → LED illuminates fully and stably within same continuous shot. Second phase: copper wire withdraws, plastic thread enters frame and makes simultaneous, stable contact across same terminals → LED remains fully unlit. Throughout, camera viewpoint is fixed, all key components (terminals, LED, wire/thread contact zone) remain continuously visible and unoccluded; lighting is uniform and reveals material surface properties.

Manual:
Experimental Procedure
1. Frame a white background with a visible broken LED circuit (two open terminals, LED mounted).
2. First, bridge the open terminals with a copper wire — ensure full contact.
3. Observe LED lighting.
4. Then, replace copper wire with a plastic thread — ensure full contact.
5. Observe LED remaining unlit.
Observation of Experimental Phenomena
LED lights only when copper wire bridges the circuit; LED remains completely unlit when plastic thread bridges the circuit.
Summary of Experimental Principles
Copper wire conducts electricity, completing the circuit and powering the LED; plastic thread is an insulator and cannot complete the circuit, so the LED stays off.

Prompt Grounding rubric:
level_1: No white background is used; no broken LED circuit loop is shown; neither a copper wire nor a plastic thread ever appears in the scene; or neither bridging action is attempted.
level_2: The white background and a broken LED circuit with two open terminals are shown, and at least one wire-like object enters the frame, but neither the copper wire nor the plastic thread can be told apart by appearance (e.g., both look like generic gray strands, or one lacks the visual traits of its stated material); or the LED sits in the frame without being wired into the loop.
level_3: The white background, the broken LED circuit with two visible open terminals, a copper wire, and a plastic thread all appear in the same scene, with the LED clearly mounted in the loop; at least one bridging attempt (copper or plastic touching both terminals) is shown, but the clip stops short of showing both materials bridging the gap in order.
level_4: Everything required for score 3 holds, and in addition: the copper wire reads as a shiny, uniform metal strand and the plastic thread reads as a dull, fibrous, non-metallic strand, so the two are easy to tell apart on sight; the copper wire bridges the two terminals first, is withdrawn, and the plastic thread bridges the same two terminals afterward, in that order; both bridging attempts hold visible contact with each terminal for a clearly sustained span rather than a brief touch-and-release.
level_5: Everything required for score 4 holds, and in addition: no stray objects, hands, or tools linger in frame once each bridging attempt is under way; the terminals and the LED stay fully visible and unobstructed through both the copper and the plastic bridging attempts; and the swap from copper wire to plastic thread between the two attempts plays out as one continuous, uncut sequence rather than jumping to a new shot.

Scientific and Causal Correctness rubric:
level_1: The LED lights up while the plastic thread bridges the terminals, or fails to light while the copper wire bridges them, or its on/off state shows no link at all to which strand is touching the terminals.
level_2: The LED's on/off state changes somewhere in the clip, but the change does not track which material is bridging the terminals (for example, it lights during the plastic-thread attempt and not the copper-wire attempt); or the LED switches state with no strand touching both terminals at all.
level_3: The LED lights only while the copper wire bridges the terminals and stays dark through the entire plastic-thread attempt; however, one flaw remains: the LED's glow flickers or pulses during copper contact, appears only faintly rather than fully lit, or the copper wire never quite completes contact with both terminals at once.
level_4: The LED lights fully and steadily for the entire time the copper wire touches both terminals, and stays completely dark for the entire time the plastic thread touches both terminals; there is no lighting before contact is made or after the wire lifts away, and no partial or flickering glow during either attempt.
level_5: The LED's behavior tracks the bridging material with no ambiguity: it switches on at the instant copper completes contact with both terminals and switches off the instant that contact breaks, and it never so much as flickers while the plastic thread bridges the same terminals for a comparable span of time; neither transition shows a delay, afterglow, or partial brightness that would blur the copper-versus-plastic distinction.

Spatiotemporal Consistency rubric:
level_1: The circuit board, terminals, or LED jump to a different spot or vanish and reappear between frames; the LED changes brightness with no wire or thread touching it; a wire or thread's position or angle jumps with no movement shown; the room's lighting swings abruptly between frames; the white background suddenly shifts color, texture, or shape with no cause; or the terminals separate from the board mid-clip.
level_2: The board and terminals stay put, but at least one of the following breaks the flow: the copper wire or plastic thread appears already touching the terminals with no entry motion shown; the LED's brightness changes without a corresponding change in contact; or a highlight on the wire or thread vanishes and reappears on the same surface without explanation.
level_3: The circuit board and its two terminals stay fixed in the same spot throughout; the copper wire and the plastic thread each move into frame and reach the terminals along a single coherent path; the LED stays visible in the same position; and the light falling on the scene and the shadows it casts keep the same direction and strength from the first bridging attempt to the second.
level_4: Everything required for score 3 holds, and in addition: the copper wire and plastic thread each glide into their bridging position smoothly, without snapping into place or overshooting and settling back; the LED stays fully visible and still-positioned throughout both attempts; neither terminal nor the LED is ever blocked from view during a bridging attempt; and no motion blur smears the exact moment contact is made or broken.
level_5: Everything required for score 4 holds, and in addition: the copper wire's and plastic thread's motion into place looks natural and fluid rather than jerky or interrupted; the LED, terminals, and both strands stay sharply rendered without briefly warping or drifting out of alignment; and nothing - hand, tool, or shadow - ever crosses in front of the terminals or the LED during either bridging attempt.