Domain: Engineering — Materials Science & Engineering
Target concept: When connected with a graphite pencil core, the LED lights up or remains off; however, it does not light up when connected with wood.

Video generation prompt: On the table, an LED circuit powered by a battery, featuring a distinct break, is alternately bridged by a graphite pencil lead and a similar wooden stick by hand.

Evaluation guide:
(i) Target concept: Electrical conductivity contrast between crystalline carbon (graphite) and cellulose-based insulator (wood) in a simple DC circuit.
Minimum mechanism: Closed-loop current path must exist for LED operation; graphite provides low-resistance path allowing electron flow; wood lacks mobile charge carriers, preventing current; battery voltage must exceed LED forward voltage threshold only when conductive path is complete.
(ii)Storyline: Frame opens on static tabletop with intact but broken LED circuit (battery, wires, LED, gap). Hand enters frame, picks up graphite lead, places it across gap → LED illuminates visibly and stably. Hand removes graphite → LED extinguishes. Hand picks up wooden stick, places it across same gap → LED remains fully off. Hand removes wood. All actions occur from fixed frontal tabletop view; no camera motion; lighting is even and shadow-consistent; LED state change is binary and synchronized to contact onset/offset; materials remain fully visible and unmoving except during intentional hand placement/removal.

Manual:
Experimental Procedure
1. Place battery-powered LED circuit with visible open break on table.
2. By hand, place graphite pencil lead across break to bridge it.
3. Observe LED illumination.
4. Remove graphite; place wooden stick across same break.
5. Observe LED remains unlit.
Observation of Experimental Phenomena
- LED lights up only during graphite contact.
- LED stays off during wooden stick contact.
- Graphite and wood are visually distinguishable (dark gray metallic vs. light brown fibrous).
Summary of Experimental Principles
Graphite is electrically conductive; wood is an insulator. Conductivity enables current flow to light LED. Insulation prevents current flow, leaving LED off.

Prompt Grounding rubric:
level_1: No battery-powered LED circuit with a visible break appears on the table, or neither the graphite pencil lead nor the wooden stick appears, or no hand is shown placing anything across the break; there is no alternation between the two materials at all.
level_2: The battery-powered LED circuit with its break is visible, but only one of the two materials (the graphite lead or the wooden stick) is ever placed across the break, or the hand never performs a clear placement action; no alternation between the two materials occurs.
level_3: The circuit with its break is visible, and the hand places the graphite lead across the break and, separately, places the wooden stick across the break, with the two materials visually distinguishable from each other; the two placements occur one after another, but only one such cycle is shown, and it is not yet clear that the hand fully removes each material before placing the other.
level_4: In addition to score 3, the hand clearly removes each material from the break before the other material is placed across it, both materials remain fully visible during their respective placements without being obstructed by anything else on the table, the circuit itself stays in the same position throughout, and the two materials are placed in a fixed spatial relationship (side by side within the same frame, on the same tabletop plane) rather than shifting position between placements.
level_5: In addition to score 4, the full alternation cycle (graphite placed, graphite removed, wood placed, wood removed) is shown with each placement and removal as a distinct, unambiguous hand action, and the hand enters and exits the frame smoothly without any material or circuit part appearing to jump between positions.

Scientific and Causal Correctness rubric:
level_1: The LED lights up while the wooden stick bridges the break, or stays off while the graphite lead bridges the break, or the LED's on/off state never changes regardless of which material is placed, or there is no visible connection between which material is in contact and whether the LED is lit.
level_2: The LED's on/off state changes, but not consistently with which material is present (for example it lights up for graphite in one placement and stays off for graphite in another), or the LED's state is too ambiguous to judge (flickering rapidly, very dim, or obscured) whenever either material bridges the break.
level_3: The LED lights up whenever the graphite lead bridges the break and stays off whenever the wooden stick bridges the break, with the LED's state clearly visible in both cases, this pattern holds for the graphite-wood alternation shown, and the state change is visibly tied to the contact within the same continuous shot rather than appearing to be spliced in from a separate take.
level_4: In addition to score 3, the LED's state is stable for the full duration each material is in contact (it does not flicker or dim partway through the graphite contact, and it never briefly glows during the wood contact), the on/off transition happens promptly when a material is placed or removed rather than after a long, unexplained delay, and the graphite shows a uniform dark gray, non-reflective, matte surface while the wood shows a dry, fibrous grain with no charring. Nothing about either material's visible surface hints that the contrast comes from contamination or damage rather than the materials themselves.
level_5: In addition to score 4, the LED's behavior is fully explained by which material bridges the break at each moment: it turns on essentially as soon as the graphite makes full contact across both wire ends (a partial, one-sided touch that doesn't complete the connection does not light it up), turns off essentially as soon as the graphite is lifted away, and stays off for the entire time the wood is in contact, with no unexplained partial glow, afterglow, or state change unrelated to a material transition; the graphite core is visibly bare with no paint, coating, or eraser residue, and the wood shows no embedded metal, moisture, or burn marks that could otherwise explain the conductivity contrast.

Spatiotemporal Consistency rubric:
level_1: The battery, LED, wires, or circuit board jump to a different position between frames with no hand touching them, the LED or wires vanish and reappear, the hand appears or disappears abruptly rather than entering and exiting the frame by visible movement, or the lighting swings abruptly (e.g., a shadow vanishes and reappears pointing a different direction) with no visible cause.
level_2: The circuit or materials remain in frame but show a visible break in physical continuity: for example the wire ends are clearly not touching either material yet the LED still appears lit, the tabletop view tilts or jumps with no camera motion shown, the hand's motion toward the break freezes and then skips ahead, or shadows on the tabletop flicker or point in an inconsistent direction from one frame to the next.
level_3: The circuit, battery, LED, wires, graphite lead, and wooden stick all stay in fixed positions on the table except when the hand is actively moving one of the two materials, and the hand's motion from picking up a material to placing it across the break, then lifting it away, reads as one continuous motion; but one minor flaw is present, e.g., the hand's fingers appear to briefly pass through part of the wire without visibly touching it.
level_4: All the continuity described in score 3 holds with no such flaw: the hand's pickup, placement, and removal motions for both graphite and wood are smooth and physically plausible, the circuit parts never appear to shift position on their own, and the hand does not appear to pass through the wires or circuit board at any point.
level_5: In addition to score 4, the entire sequence (both materials being picked up, placed across the break, and lifted away) reads as one continuous, physically coherent series of hand motions with no jumps, freezes, or unexplained repositioning of the circuit, materials, or hand at any point; the tabletop remains level and planar, and the hand, materials, and circuit keep a consistent scale and perspective as the hand moves; no motion blur obscures the LED's on/off state or which material is being held; there is no ghosting, smearing, or duplicated afterimage of the hand or materials between frames; and there are no dropped frames or temporal skips: the whole shot plays back fluidly from start to end.