Domain: Natural Science — Physics
Target concept: Overlapping circular wave patterns from two slits in a water tank

Video generation prompt: A shallow water wave tank contains a rigid barrier with two narrow, parallel slits. A single planar wave travels across the water surface toward the barrier and reaches the two slits.

Evaluation guide:
(i) Target concept: Two-source coherent wave interference in shallow water.
Minimum mechanism: A planar incident wave must strike a barrier with two narrow, identical, closely spaced, parallel slits; each slit must act as an independent circular wave source; resulting waves must be coherent, same wavelength/frequency, and propagate in same medium to enable stable superposition.
(ii)Storyline: [Frame 0–2] Still water surface + stationary double-slit barrier fully visible + incident wave front approaching barrier from one side; [Frame 3–5] Incident wave contacts barrier; wave energy passes only through two slits; [Frame 6–8] Two distinct circular wave fronts emerge synchronously from slit centers, expanding radially; [Frame 9–10] Overlapping region forms with visible amplitude modulation: dense crests (constructive) and flattened/suppressed zones (destructive); all observed from fixed frontal orthographic or slightly elevated viewpoint with no occlusion.

Manual:
Experimental Procedure
1. Fill a shallow rectangular transparent water tank with still water.
2. Place a rigid double-slit barrier vertically in the tank, centered and perpendicular to one long side.
3. Generate a single straight incident wave front from that side, traveling toward the barrier.
Observation of Experimental Phenomena
Two identical circular wave patterns emerge from the two slits and expand outward; they overlap beyond the barrier, forming alternating regions of larger and smaller wave amplitude — a stable interference pattern.
Summary of Experimental Principles
Wave superposition: when coherent waves pass through two narrow slits, they act as new coherent sources; their circular wavefronts interfere constructively (in-phase) and destructively (out-of-phase), producing a characteristic pattern governed by path difference.

Prompt Grounding rubric:
level_1: No water tank is visible; no barrier with slits is present; no incident wave appears; no wave pattern of any kind is visible anywhere in the frame.
level_2: A water container is present and a wave-like disturbance appears, but there is no identifiable barrier with two distinguishable slit openings, and the disturbance does not originate near two separated openings.
level_3: A shallow rectangular water tank is visible; a rigid barrier is present, oriented perpendicular to the incident wave direction, with two distinct slit openings clearly visible in it; a single incident wave front approaches the barrier from one side.
level_4: All of score 3, and the incident wave front reaches the barrier, and two separate wavefronts become visible originating right at the two slit openings themselves (not from the barrier's edges, a single point, or any other location).
level_5: All of score 4, and the tank, barrier, and both slit openings stay fully visible and correctly positioned throughout the sequence in a single fixed viewpoint, with no cut, no repositioning of the barrier, and no obstruction of the slit region at any point.

Scientific and Causal Correctness rubric:
level_1: There is no causal link between the wave reaching the barrier and new waves appearing: waves appear before contact, or emanate from the barrier's edges or a single point rather than from the two slit gaps, or show no circular (radial) geometry at all.
level_2: Two new wave sources may be visible, but they behave unphysically for two-slit diffraction: only one slit produces an outward wavefront while the other does not, or both wavefronts share a single common center rather than two centers spaced apart by the slit separation, or the wavefronts are non-circular (elliptical, linear, or jagged).
level_3: Both slit-sourced wavefronts expand as circular arcs at the same rate and reach the region where they should cross, but no amplitude change (no brightening, flattening, or crest/trough pattern) is visible where the two wavefronts meet; the waves appear to pass through each other with no sign of superposition.
level_4: Where the two circular wavefronts cross, the water surface visibly shows amplitude variation consistent with superposition (some patches show reinforced, taller or brighter crests and other patches show reduced or flattened surface motion), but the arrangement of these patches is not yet clearly symmetric about the midline between the two slits.
level_5: The amplitude variation in the overlap region forms a clear, sustained pattern of alternating reinforced and suppressed zones (bright fringes where crests align, calmer zones where crest meets trough) that is symmetric about the centerline between the two slits, and this fringe pattern stays phase-stable rather than flickering randomly as the waves continue to expand.

Spatiotemporal Consistency rubric:
level_1: The barrier appears or disappears partway through the sequence; the water surface resets to still water and starts over; a wave pattern jumps to a different position or suddenly reverses direction; the camera viewpoint shifts or rotates with no in-scene cause.
level_2: The two slit openings appear to shift position relative to the barrier between frames; a wavefront's center drifts away from its slit opening as it expands rather than staying anchored there; the water surface's texture changes abruptly (e.g., smooth ripples suddenly look grainy, then smooth again); or the shadow the barrier casts on the tank floor swaps to the opposite side with no change in the light source's position.
level_3: The barrier stays fixed in position and orientation; the water surface keeps a consistent texture and reflectivity; both circular wavefronts stay anchored at their slit openings and expand outward continuously with no pause, reversal, or sudden collapse; nothing in the scene teleports or changes shape without a physical cause.
level_4: All of score 3, and the two wavefronts keep a constant separation between their centers as they expand, matching the fixed slit spacing; neither wavefront's circular shape becomes distorted while propagating; there is no sudden jump in brightness or contrast that would obscure the waves; the whole expansion reads as smooth, unbroken motion across the sequence.
level_5: All of score 4, and the interference fringes in the overlap region (the alternating brighter and calmer bands) keep a visually steady spacing as the waves expand, with no fringe suddenly popping in or out or flickering erratically, no dropped or frozen-looking frames, and the camera viewpoint never pans, tilts, zooms, or cuts away from the tank.