Domain: Engineering — Agricultural Engineering
Target concept: When a corn leaf (a monocot) is laid flat and observed, its venation exhibits a straight, parallel arrangement without reticulate branching, which is its distinctive visual characteristic.

Video generation prompt: Place a fresh corn leaf flat on a table, gently smooth it with fingers, and observe its surface from above to demonstrate the plant's morphology. Highlight its elongated leaf shape and illustrate the multiple veins arranged from the leaf base to the leaf tip.

Evaluation guide:
(i) Target concept: Monocot leaf identification via parallel venation morphology.
Minimum mechanism: A fresh, turgid Zea mays leaf must be physically placed and mechanically smoothed to eliminate curvature artifacts, enabling unambiguous visual resolution of intrinsic parallel venation under stable overhead illumination.
(ii)Storyline: [Phase 1: Placement] Leaf lands flat on table surface with base aligned toward camera bottom and tip toward top. [Phase 2: Smoothing] Fingers move unidirectionally from base to tip, applying light pressure; leaf surface flattens without buckling. [Phase 3: Stabilization] Fingers fully retract; leaf remains motionless and flat. [Phase 4: Observation] Overhead static shot holds full leaf in focus; parallel veins are continuously visible across entire length. [Visibility constraint] All phases occur within single fixed overhead frame; no occlusion, no cutaway, no change in viewpoint or zoom.

Manual:
Experimental Procedure
1. Place a fresh, green corn leaf flat on a clean table surface.
2. Gently smooth the leaf surface with fingertips from base to tip.
3. Observe from directly overhead to view the elongated shape and parallel venation.
Observation of Experimental Phenomena
The leaf exhibits a long, narrow shape; multiple straight, evenly spaced veins run continuously and parallel from base to tip with no branching or reticulation.
Summary of Experimental Principles
Corn is a monocot; its leaves display parallel venation — a defining morphological trait distinguishing monocots from dicots.

Prompt Grounding rubric:
level_1: No corn leaf appears in the shot at all; or the object shown is not a fresh, intact green monocot leaf with an elongated, tapering shape (e.g., it is a broad dicot-shaped leaf, an artificial/plastic prop, or a wilted brown leaf); or the leaf is never laid flat on a table surface; or the camera never holds a top-down overhead angle; or fingers never make visible contact with the leaf to smooth it.
level_2: A green, corn-like leaf sits on a tabletop and the camera is roughly overhead, but the setup diverges from the prompt in a clear way, e.g., the leaf is curled, folded, or propped at a visible tilt of more than roughly 30 degrees from horizontal rather than lying flat; or the finger contact is a hard press, pinch, or grab rather than a gentle smoothing pass; or the viewpoint is side-on or oblique enough that the leaf's full elongated shape is not visible from above.
level_3: A fresh green corn leaf is placed flat on the table, fingers make a visible gentle pass across the blade to smooth it, and a top-down camera keeps the leaf's full elongated, base-to-tip shape in frame, with the actions occurring in the order place → smooth → observe.
level_4: All conditions for score 3 are met, AND once the fingers finish the smoothing pass they lift fully out of contact with the leaf and do not return during the observation portion of the shot, AND the whole blade, from its base to its tapering tip, stays inside the frame without any part sliding off-screen or being blocked from view, AND the leaf does not curl back up, lift at an edge, or slide out of its smoothed position once the fingers are gone.
level_5: All conditions for score 4 are met, AND the blade lies fully flat with no visible wrinkles, buckles, or crease lines left over from the smoothing pass, AND the two long edges of the blade run straight along its length without visibly bowing, twisting, or narrowing/widening in a way that misrepresents its true tapered shape, AND the overhead framing keeps the leaf centered rather than drifting toward one end of the blade, AND no object besides the leaf, the tabletop, and the smoothing hand ever appears in the frame.

Scientific and Causal Correctness rubric:
level_1: The leaf shown is not consistent with a monocot grass leaf at all, e.g., it has a branching, web-like (reticulate) vein network typical of a broadleaf/dicot, or no venation is visible/depictable, or the leaf is an obviously artificial, dried, or discolored (brown/yellow) prop rather than a fresh green blade.
level_2: The leaf is green, elongated, and grass-like, but its venation is shown incompletely or incorrectly for a monocot, e.g., visible veins cross one another, converge toward a point, or fork mid-blade; or veins are only legible over a small patch rather than along the blade's length; or tears/holes in the leaf break up the vein lines so the parallel pattern cannot be judged.
level_3: The leaf reads as a fresh, intact corn leaf: elongated and tapering to a point, with several fine veins running the full visible length of the blade, all oriented parallel to one another and to the leaf's long axis, with no vein forking, crossing, or net-like branching anywhere on the blade.
level_4: All conditions for score 3 are met, AND the parallel veins stay sharp and individually distinguishable across the whole blade, not washed out by glare, blur, or shadow near either end, AND no cross-links or secondary veinlets connect adjacent parallel veins anywhere (i.e., no ladder-like reticulate pattern appears), AND the leaf margin is smooth and untoothed rather than lobed or serrated, matching a real corn leaf edge.
level_5: All conditions for score 4 are met, AND a single central midrib is clearly visible running the full length of the blade, distinctly thicker and often lighter-toned than the many finer parallel veins on either side of it (matching real Zea mays morphology, where the midrib is the most prominent vein on the leaf) rather than being missing, faint, or blended in so it can't be told apart from the lateral veins, AND the spacing between the fine parallel veins looks even from the leaf's base to its tip, without visibly crowding together or fanning apart, AND the blade surface has the smooth, faintly glossy look of a fresh corn leaf cuticle rather than a dull, fuzzy, or heavily waxy appearance.

Spatiotemporal Consistency rubric:
level_1: The leaf or the smoothing hand jumps to a clearly different position or orientation between frames with no continuous motion linking the two (a teleport); or the leaf blade appears from nowhere or vanishes outright partway through the shot; or the blade visibly splits into two leaves or duplicates itself; or the scene abruptly swings from daylight-level brightness to near darkness (or the reverse) with nothing on screen to explain it.
level_2: The leaf shifts across the tabletop by roughly a quarter of its own length or more between frames with no visible hand motion causing the move; or the fingers reappear in a new spot on the leaf with no visible path connecting the old and new positions; or the leaf blade behaves like stretchy rubber, or instantly crumples and unfurls, rather than bending the way a real corn leaf would under light finger pressure.
level_3: Small, low-impact inconsistencies appear without changing the overall reading of the scene, e.g., a slight tremble in the overhead framing, a brief motion blur during the finger's smoothing pass, or a momentary tremor at the leaf's edge while being smoothed that settles back to flat shortly after.
level_4: All conditions for score 3 are met, AND there is no visible jump-cut, frame skip, or stutter in the motion of the hand or the leaf, AND the fingers follow a single natural, continuous path while smoothing rather than snapping to a new position or moving with a stop-start rigidity, AND any temporary buckling of the leaf under the fingers fully relaxes back to flat before the observation phase begins, AND the shadow the leaf casts on the tabletop stays on the same side and keeps roughly the same shape throughout, consistent with one fixed overhead light rather than shifting as though the light source itself were moving.
level_5: All conditions for score 4 are met, AND the leaf shows no visually perceptible sliding or shifting on the table once the fingers lift away for the observation phase, AND the finger motion during smoothing eases in and out naturally (gradually speeding up and slowing down rather than snapping instantly to full speed or halting dead), AND the brightness on the leaf's surface stays even across the blade with no sudden bright flash or dark patch appearing without cause, AND the sense of depth and scale between the leaf and the tabletop stays consistent, with no warping or swimming of the background while the camera holds its static overhead position.