Domain: Natural Science — Morphology
Target concept: Sexual dimorphism in Asian elephants: Males possess long and thick tusks, whereas females lack tusks.

Video generation prompt: Two Asian elephants are walking side by side on the grassland; the one on the left is female, and the one on the right is male. Observe and compare the morphological differences between these two elephants. The image mainly presents the two elephants from the front.

Evaluation guide:
(i) Target concept: Sexual dimorphism in Asian elephants (Elephas maximus) typically manifests as tusk presence in adult males and tusk absence in adult females, though this pattern is not universal.
Minimum mechanism: Tusk growth is sex-linked and hormonally influenced; adult female Asian elephants normally do not grow externally visible tusks, and most adult males do grow prominent tusks. However, naturally tuskless adult males ('makhna') are a documented, non-trivial phenotype in some populations, notably in Sri Lanka, so tusk presence should be read as the typical, majority male pattern rather than a biologically universal rule. For this demonstration, the depicted male is a tusked individual, consistent with the majority male phenotype.
(ii)Storyline: Frame opens on a static front-facing grassland scene -> two Asian elephants enter or are revealed side by side -> camera holds a fixed frontal view -> observer visually isolates the left elephant (no tusk structures visible at the upper jaw) -> observer visually isolates the right elephant (two prominent, continuous, symmetrical ivory tusks clearly emerging from the upper jaw) -> the comparative contrast is sustained for the full duration -> viewpoint remains stable, with no occlusion and no morphological ambiguity.

Manual:
Experimental Procedure
1. Position two Asian elephants side by side on open grassland.
2. Orient the camera directly front-facing to capture the full head and upper torso.
3. Ensure the left elephant is female (tuskless) and the right elephant is male (tusked).
Observation of Experimental Phenomena
- The left elephant shows no tusk structures emerging from the upper jaw.
- The right elephant shows two continuous, thick, straight-to-slightly-curved ivory-colored tusks emerging symmetrically from the upper jaw.
- Both elephants display rounded ears, a compact skull, and a single dorsal head ridge, distinct from African elephants.
Summary of Experimental Principles
Sexual dimorphism in Asian elephants: most adult males grow long, thick tusks, and adult females typically lack tusks. Naturally tuskless adult males ('makhna') are a documented, non-trivial phenotype in some populations, such as Sri Lanka, so this pattern should be read as the typical majority rule rather than a biologically universal one.

Prompt Grounding rubric:
level_1: Fewer than two elephants appear, or only one Asian elephant is visible; or the elephants are not shown on grassland; or the viewpoint never becomes front-facing; or the two elephants are never arranged side by side.
level_2: Two elephants appear side by side on grassland, but at least one does not match Asian elephant body shape (e.g., it has the very large, fan-like ears of an African elephant); or one elephant is missing from the frame for more than half the clip; or the left/right placement does not match the stated labels (e.g., the female elephant ends up standing on the right).
level_3: Two Asian elephants stand side by side on grassland, viewed from the front; the left elephant and the right elephant are each clearly identifiable as elephants; neither elephant is misidentified as a different species, and the grassland setting is maintained.
level_4: Everything required for score 3 holds, and the left elephant stays in the left half of the frame and the right elephant stays in the right half throughout the clip; both elephants remain fully within frame without being cropped at the edges; neither elephant blocks the view of the other's head or upper body; the grassland background stays visually continuous behind both.
level_5: Everything required for score 4 holds, and the left elephant stays continuously and exclusively in the left portion of the frame while the right elephant stays exclusively in the right portion, with the side-by-side arrangement held steady — neither elephant drifts toward the center, rotates out of the frontal view, or swaps sides; no unrelated object or scene cut is inserted into the shot.

Scientific and Causal Correctness rubric:
level_1: Neither elephant shows tusks; or both elephants show tusks; or tusks appear on the left (female) elephant instead of the right (male) elephant; or the tusks shown are anatomically implausible (e.g., extremely thin, sharply curled, or broken into disconnected pieces).
level_2: Tusks are visible on only one elephant, but appear on the left (female) elephant rather than the right; or the right (male) elephant's tusks are present but broken, or not visible for more than half the clip; or a tusk appears on the female elephant even briefly, contradicting the sex labeling.
level_3: The right (male) elephant shows two continuous, thick tusks with a straight-to-slightly-curved shape and an ivory color; the left (female) elephant shows no tusks emerging from the upper jaw when viewed from the front; both elephants show Asian elephant features (rounded ears, a single dorsal head bump, a compact skull profile rather than the concave back and large ears of an African elephant).
level_4: Everything required for score 3 holds, and the left elephant shows no tusk stubs, buds, or small protrusions where tusks would emerge; the right elephant's two tusks are roughly symmetrical, clearly emerge from the upper jaw rather than the trunk or forehead, and keep a fairly even thickness along their visible length; neither elephant shows a feature that contradicts Asian elephant anatomy (e.g., no oversized, fan-like ears or a concave back typical of African elephants).
level_5: Everything required for score 4 holds, and the left elephant shows a complete absence of any tusk-related structure at the upper jaw; the right elephant's tusks are fully visible, unbroken, and unobstructed for the whole clip, standing out clearly among its facial features; both elephants' ear shape, forehead contour, and body proportions consistently match documented Asian elephant morphology rather than any other elephant species.

Spatiotemporal Consistency rubric:
level_1: One or both elephants jump to a different position with no walking motion shown in between; or one of the two elephants is missing from the frame for a stretch of the video with no walking-away motion shown, and then is back in the shot; or a leg, ear, or trunk visibly bends or splits in an anatomically implausible way; or the shadows cast by the elephants change direction abruptly with no matching change in a visible light source.
level_2: One elephant's position shifts by roughly a third of its own body width relative to the other elephant at some point in the clip without a walking motion to explain it; or tall grass intermittently and fully hides a tusk for more than a couple of seconds; or an elephant's feet appear to float above the grass or sink into it without the grass visibly compressing.
level_3: The two elephants keep the same side-by-side spatial relationship throughout; neither elephant vanishes or jumps position; any motion is a continuous, plausible walking gait; neither elephant's body shows a visible break or tear (limbs, trunk, and face all stay intact and connected); the direction of the light and shadows on both elephants looks the same from the start of the clip to the end.
level_4: Everything required for score 3 holds, and any walking motion looks biomechanically plausible for a large quadruped (slow, alternating leg swing, weight shifting between steps); the grass beneath each elephant's feet visibly bends or compresses as it steps rather than staying rigid and unaffected; the camera does not suddenly zoom, pan, or change angle; neither elephant shows visible flicker or a stutter in its motion.
level_5: Everything required for score 4 holds, and the left elephant stays visibly within the left half of the frame while the right elephant stays visibly within the right half for the entire clip, without either one drifting noticeably toward the center or crossing to the other side; the elephants' motion stays smooth and at a steady pace with no freezing or sudden speed change; the grass they step on visibly springs back after each step; the shadows both elephants cast stay consistent with a single, unchanging light direction throughout.