Domain: Engineering — Materials Science & Engineering
Target concept: Steel nail scratch on softwood vs. stone tile surface

Video generation prompt: On a workbench, one hand dragged the same steel nail across a piece of soft pine wood and then across a stone tile with similar force.

Evaluation guide:
(i) Target concept: Relative scratch resistance of three materials that are conventionally rated on different hardness/indentation scales.
Minimum mechanism: The steel nail (Vickers hardness roughly HV 600–800) is softer than the stone tile (e.g., granite or porcelain, Vickers hardness roughly HV 650–750), so the nail cannot permanently scratch the stone; the nail is far harder than the soft pine, which is instead rated on the Janka scale (roughly 380 lbf, a measure of resistance to denting/embedding rather than of scratch hardness, and not numerically interconvertible with Vickers units); these two scales test different properties, but together they support the same visible outcome: softwood must undergo visible plastic deformation (fiber separation/compression), while the stone tile must resist permanent deformation (no groove, no spalling).
(ii)Storyline: [Frame 0] Nail held above softwood on workbench; [Frame 1–3] Nail contacts softwood and begins dragging → immediate fiber lifting/groove formation; [Frame 4–5] Nail transitions continuously from softwood to stone tile (no lift-off); [Frame 6–8] Nail drags across stone tile → no groove, no debris, no discoloration; [Frame 9] Nail exits stone tile; all events occur from fixed frontal/slightly oblique viewpoint with full visibility of nail tip, both surfaces, and hand grip; no occlusion, no cut, no perspective shift.

Manual:
Experimental Procedure
1. Place a flat piece of soft pine wood and a flat stone tile side-by-side on a stable workbench.
2. Hold a steel nail by its head with one hand.
3. Drag the nail point-first across the softwood surface with steady pressure.
4. Without lifting the nail fully, continue dragging it across the stone tile surface using similar force.
Observation of Experimental Phenomena
- Softwood shows a continuous, shallow groove with lifted wood fibers and light discoloration along the path.
- Stone tile shows no groove, no material removal, and at most a faint, discontinuous scuff or no visible mark.
Summary of Experimental Principles
- Softwood has low hardness and a heterogeneous fibrous structure → yields under point load, allowing visible plastic deformation.
- Porcelain stone tile is a fine-grained, largely amorphous ceramic with a genuinely isotropic structure and no cleavage planes, so it resists scratching almost uniformly in every direction; granite is a polycrystalline rock containing quartz, feldspar, and mica -- some of which (feldspar, mica) do have their own cleavage planes -- but its interlocking crystal matrix as a whole still presents a much harder, more rigid surface than the steel nail (Vickers hardness roughly HV 600–800), so it likewise resists being scratched or grooved.

Prompt Grounding rubric:
level_1: No steel nail, no soft pine wood, no stone tile, or no workbench visible; at least two of the three core objects (nail, softwood, stone tile) are absent or unidentifiable; action sequence is missing entirely (e.g., only one surface shown, or no dragging motion).
level_2: Exactly one of the three core objects (steel nail, soft pine wood, stone tile) is present and correctly identifiable; workbench is visible but only one surface is shown; dragging action occurs on a single surface only, with no sequential transition between surfaces.
level_3: All three core objects present and visually identifiable: steel nail (metallic gray/silver, rigid, pointed), soft pine wood (light tan/brown, grain-visible, flat rectangular piece), stone tile (gray/beige, uniform texture, rigid, non-porous); workbench visible as a flat horizontal support surface; the nail is dragged across one surface then the other in sequential order; both dragging actions occur within the same continuous shot.
level_4: Everything required at level 3 holds, AND the spatial arrangement is preserved: both surfaces sit adjacent to each other on the same workbench, in a side-by-side or immediately consecutive arrangement; the same hand grips the nail in the same orientation for both dragging actions, and the nail follows a consistent, matching direction of travel across both surfaces.
level_5: Everything required at level 4 holds, AND every core object keeps its identifying visual features fully consistent throughout: the nail's metallic color and shape, the softwood's grain pattern and tan color, and the stone tile's texture and color never change or swap between the two dragging actions; the workbench surface, lighting setup, and camera framing established at the start of the sequence remain the same recognizable setup at the end.

Scientific and Causal Correctness rubric:
level_1: Phenomenon contradicts materials science: e.g., identical visible scratch depth/texture on both surfaces; nail visibly deforms, bends, or chips; softwood shows no scratch or indentation while stone tile shows deep groove; or stone tile shows powder/dust while softwood shows none.
level_2: At least one surface shows physically impossible scratch behavior: e.g., stone tile exhibits a long continuous white scratch mark (like chalk on slate), or softwood shows no surface disturbance whatsoever (no fiber lifting, no groove, no discoloration); or a scratch appears before contact or persists after the nail leaves the surface.
level_3: Scratch phenomenon is visibly differentiated: softwood shows a continuous, shallow, fibrous groove with lifted wood fibers or light discoloration along the path; stone tile shows either no visible mark OR a faint, discontinuous, shallow scuff (no groove, no material removal); both scratches appear only during and immediately after nail contact, with no post-contact persistence.
level_4: Everything required at level 3 holds, AND causal fidelity holds: scratch appearance is temporally locked to nail contact (no scratch appears before contact begins or after contact ends); the scratch on the softwood is clearly deeper and more continuous than any mark on the stone tile; no mark appears on the stone tile unless the nail is in direct contact with it -- no 'ghost' marks or misaligned traces.
level_5: Everything required at level 4 holds, AND the surface-specific material response is fully accurate: the softwood scratch shows localized fiber separation and a slight compression ridge on one side of the groove; the stone tile shows zero groove, zero debris, and zero discoloration -- at most a subtle matte scuff, or no visible change at all; no artifact such as a smudge, blur, or reflection is mistakable for a scratch on the stone tile.

Spatiotemporal Consistency rubric:
level_1: The nail (or another core object) jumps from one point to a clearly different point without passing through the space in between, as if it had been lifted and set down elsewhere in an instant; the workbench surface abruptly changes texture or orientation between frames; the scene's brightness shifts drastically within what should be a single continuous shot, with no cut to explain it; the nail or the hand vanishes and then is back again with no visible cause; the hand reappears holding the nail in a different grip with no visible transition; the two surfaces swap positions or change size inconsistently between frames.
level_2: Multiple moderate continuity breaks occur: the shot cuts away from the action and back more than once, breaking what should be one continuous take; the nail or the hand flickers in and out of visibility across a few frames; the view of the workbench switches between a front-facing angle and an overhead angle within what should be one continuous shot; the softwood's surface appearance changes abruptly (e.g., looks wet in one moment and dry the next) with no visible cause.
level_3: Minor but noticeable spatiotemporal flaws: the nail tip is briefly hidden behind the hand for a moment that is short but still noticeable; a highlight or reflection on the nail or the stone tile blinks out and then reappears once; aside from these, the workbench stays fixed in position and orientation, and all objects keep consistent relative size and placement across the sequence; the nail moves from the softwood to the stone tile as one continuous action, without a hard cut or an unexplained repositioning.
level_4: Everything required at level 3 holds, AND the nail's motion across both surfaces is smooth and physically plausible, without sudden jerks or unnatural changes in speed; the hand's grip and wrist motion look like a natural human dragging motion rather than a rigid, mechanical slide; the nail stays visible for the full duration of both dragging actions without being cut from view or blocked from sight by the hand or any other object; the surface of the softwood and the stone tile keeps a consistent, undistorted texture throughout the motion, without visibly warping, stretching, or breaking up into a blurred or blocky pattern.
level_5: Everything required at level 4 holds, AND the entire sequence, from first contact with the softwood to departure from the stone tile, plays out with no pause, no reversal, and no repeated pass; the nail moves directly from the softwood onto the stone tile without vanishing, reappearing, or jumping to a new position; the camera's viewpoint, zoom, and focus never change across the whole sequence; the nail, hand, and both surfaces remain continuously visible, with no flickering, freezing, or unexpected obscuring at any point.