Domain: Natural Science — Geology & Geophysics
Target concept: Mohs hardness scratch test: Quartz scratches glass and softer minerals.

Video generation prompt: A hand performs the same motion, scratching a glass plate and a softer mineral with a sharp quartz crystal.

Evaluation guide:
(i) Target concept: Relative hardness comparison via controlled mechanical abrasion.
Minimum mechanism: Quartz (Mohs 7) must be harder than both reference materials it contacts, the glass plate (~5.5–6) and the softer mineral (e.g., calcite ≈3 or gypsum ≈2), so that identical normal force and tangential motion produce a visible scratch on both surfaces; scratch formation depends on localized brittle removal along the stroke path, not cutting or chiseling.
(ii)Storyline: 1. Hand enters frame holding sharp quartz crystal. 2. Quartz tip contacts glass plate and executes a single linear stroke → a visible scratch appears on the glass. 3. Without repositioning the camera or resetting the hand, the quartz tip contacts the adjacent softer mineral and executes an identical stroke → a visible scratch also appears on the softer mineral. 4. Final frame holds both substrates in view, confirming that quartz scratches both surfaces, consistent with quartz ranking above both on the hardness scale. Perspective: Fixed frontal or slight oblique angle; full hand, quartz tip, and both substrate surfaces must remain simultaneously visible and unoccluded throughout.

Manual:
Experimental Procedure
1. A hand holds a sharp, naturally faceted quartz crystal.
2. The hand performs an identical linear scratching motion across a clean glass plate and a visibly softer mineral (e.g., calcite or gypsum), placed side-by-side in the same frame.
3. Motion is steady, direct, and repeated with same stroke length and pressure impression.
Observation of Experimental Phenomena
- A clear, continuous scratch appears on the glass plate.
- A clear, continuous scratch also appears on the softer mineral.
Summary of Experimental Principles
Quartz (Mohs hardness 7) is harder than both the glass plate (~5.5–6) and softer minerals such as calcite (3) or gypsum (2); a mineral can scratch any material with lower Mohs hardness than itself, so quartz visibly scratches both surfaces in this test.

Prompt Grounding rubric:
level_1: No sharp quartz crystal appears; or no hand performs a scratching motion; or the glass plate is missing; or the softer mineral is missing; or the glass plate and the softer mineral are never shown close enough together to be scratched in the same continuous shot.
level_2: A quartz crystal appears but no hand is holding it; or a hand appears but never touches either surface; or only one of the two substrates (the glass plate or the softer mineral) is shown, not both; or the two substrates never appear together in the same shot.
level_3: A hand holds a sharp quartz crystal and performs a linear scratching motion across both the glass plate and the softer mineral; both substrates are visibly present and distinguishable from one another; the motion happens in one scene with a fixed camera view; the glass plate and softer mineral sit close enough together to be reached by the same hand without repositioning.
level_4: Everything at the 3-point level holds, and further: the scratching motion is applied to the glass plate and then to the softer mineral (or the reverse order) within one continuous take; the quartz crystal stays visibly sharp and unchanged in shape before, during, and after each contact; no tool or substrate is swapped out partway through.
level_5: Everything at the 4-point level holds, and further: the hand repeats essentially the same motion (same direction, stroke length, and apparent pressure) on both substrates; the quartz crystal keeps the same orientation and grip throughout; both substrates stay in place and fully in frame, with no repositioning or cut between the two contacts.

Scientific and Causal Correctness rubric:
level_1: No visible scratch appears on either the glass plate or the softer mineral; or a scratch appears on the softer mineral but the glass surface stays completely smooth and unmarked (i.e., quartz appears unable to scratch glass, which reverses the real hardness ranking); or a scratch appears on the glass but not on the softer mineral; or both surfaces show identical, indistinguishable marks with no way to tell one scratch from the other.
level_2: A scratch appears on both the glass plate and the softer mineral, but one of the two marks is too faint or ambiguous to confirm (e.g., a very slight mark on the glass that could be a reflection artifact rather than a genuine scratch) while the other is unambiguous; or a scratch eventually appears on both, but only after the stroke has clearly ended, with no visible link between the motion and the mark's appearance.
level_3: Distinguishable scratches appear on both surfaces: a visible linear scratch appears on the glass plate, and a visible linear scratch appears on the softer mineral, each appearing during or immediately after the quartz crystal's contact with that surface.
level_4: Everything at the 3-point level holds, and further: each scratch is continuous, linear, and follows the path of the quartz tip's motion across that surface; no scratch appears anywhere else on either substrate; neither substrate shows damage beyond a scratch, such as chipping, cracking, or powdering.
level_5: Everything at the 4-point level holds, and further: the quartz crystal itself shows no visible wear, chipping, or dulling after scratching either surface; the glass plate stays otherwise optically clear and transparent apart from the scratch line; the softer mineral's scratch is visibly deeper or more pronounced than the mark on the glass, consistent with it being softer than both quartz and glass.

Spatiotemporal Consistency rubric:
level_1: Severe breaks in continuity: the hand, the quartz crystal, or either substrate jumps to a new position between frames; the camera viewpoint or zoom level jumps suddenly; the glass plate or the softer mineral vanishes and reappears; the scene's overall brightness flips suddenly partway through a stroke; the quartz crystal's position or orientation changes with no visible path connecting the two states.
level_2: Noticeable but less severe glitches: the hand or quartz crystal jitters or briefly jumps during the stroke; either substrate shifts position slightly between the two contacts; the contact point between the quartz tip and a surface is hidden for more than a moment with no recovery; the direction or strength of the shadows changes partway through the sequence.
level_3: The hand moves without interruption from its initial grip through the first contact and on to the second contact; the quartz tip stays in contact with each surface for the whole length of its scratching stroke; both substrates stay fully visible and stationary throughout; the direction and brightness of the light on the scene do not change from one contact to the next.
level_4: Everything at the 3-point level holds, and further: the hand's motion is smooth and unbroken across both scratching strokes; there is no visible cut, splice, or repeated frame; neither the hand, the quartz crystal, nor either substrate stretches, warps, or pops in and out of shape.
level_5: Everything at the 4-point level holds, and further: the quartz tip stays aligned with the direction of motion at all times; the distance between the hand and each substrate looks consistent throughout; the glass plate and softer mineral keep the same fixed positions relative to each other across the whole video, with no drift; no edges or textures misalign from one frame to the next.