Domain: Natural Science — Physics
Target concept: Water wave diffraction

Video generation prompt: A barrier with a narrow slit is placed in a water tank. A point source on the left generates stable circular water waves, which pass through the narrow slit. The propagation pattern of the waves after passing through the slit is observed from directly above the tank, looking straight down at the water surface.

Evaluation guide:
(i) Target concept: Single-slit diffraction of mechanical water waves as a model for wavefront regeneration via Huygens’ principle.
Minimum mechanism: Water must behave as a continuous, incompressible, low-viscosity medium; barrier must be rigid and impermeable except at slit; point source must generate periodic, isotropic disturbances; slit width must be small relative to wavelength to enable observable spreading.
(ii)Storyline: [Frame 0–2] Still water surface, barrier upright, point source inactive at left. → [Frame 3–4] Point source activates; circular wavefronts expand outward from source. → [Frame 5–7] Waves reach barrier; most reflect, but a narrow portion transmits through slit. → [Frame 8–10] Post-slit wavefronts emerge radially symmetric about slit center, visibly distinct from pre-slit origin; all observed from a fixed top-down (plan) view directly above the tank, with no occlusion of the water surface.

Manual:
Experimental Procedure
1. Fill rectangular water tank with still water.
2. Place vertical barrier with single narrow slit at center of tank.
3. Position point source at left edge, submerged just below surface.
4. Activate source to emit stable circular waves.
Observation of Experimental Phenomena
Before slit: concentric circular wavefronts centered on point source.
After slit: circular wavefronts centered on slit location — same frequency, reduced amplitude, radially symmetric.
Summary of Experimental Principles
Narrow slit acts as new wave source due to Huygens’ principle; diffraction occurs when slit width ≈ wavelength; resulting wavefronts spread isotropically in 2D.

Prompt Grounding rubric:
level_1: No water tank, barrier, slit, or point source is visible, and no wave activity of any kind appears on the water surface; the scene bears no resemblance to the described ripple-tank setup.
level_2: Only some of the required objects appear (e.g., the tank and point source exist but the barrier or its slit is missing, or the point source is not positioned on the left side of the tank), or no waves are generated at all; the described spatial layout (source on the left, barrier with a narrow slit) is not established.
level_3: Viewed from directly above the water tank, a barrier spanning the tank with a single narrow slit is visible; a point source sits on the left side of the tank and continuously emits circular ripples; the ripples travel toward the barrier and some portion passes through the slit, but the pattern emerging beyond the slit is not visually distinguishable in shape from the ripples arriving at the barrier (i.e., no evidence yet that the slit itself is reshaping the wavefronts).
level_4: Everything required for score 3 is shown, and in addition the ripples arriving at the barrier are clearly circular arcs centered on the point source, while the ripples beyond the slit visibly originate from the slit opening itself rather than continuing to trace circles centered on the point source; i.e., the video depicts the correct source–slit–observation-zone layout described in the prompt, with the slit acting as the apparent new origin of the downstream ripples.
level_5: Everything required for score 4 is shown, and in addition the slit opening is unambiguously narrow relative to the barrier's overall length, the point source stays in one place and keeps emitting ripples at a steady rate for the whole clip, and the top-down framing keeps the entire tank, barrier, slit, and point source in view without cropping: full adherence to the posted prompt's described objects and layout.

Scientific and Causal Correctness rubric:
level_1: No physically coherent wave behavior is shown: e.g., ripples travel in straight lines rather than circular arcs, no wavefronts are visible on either side of the slit, or the waves vanish and reappear with no causal link to the point source or the slit.
level_2: Circular ripples radiate from the point source before reaching the barrier, but at the slit the behavior is unphysical: the ripples either stop entirely at the barrier, reflect back with no transmission through the slit, or pass straight through the slit as a narrow undeviated beam with no spreading beyond the opening; none of this is consistent with diffraction.
level_3: Circular ripples radiate from the point source, reach the barrier, and a portion passes through the slit; beyond the slit the wavefronts do spread out, but the spreading is lopsided or beam-like rather than centered on the slit (e.g., the ripples continue to bulge mainly in the point source's original direction rather than curving around into new arcs centered at the opening), so the slit does not yet read as a fresh, independent wave origin.
level_4: The lopsided spreading described at score 3 has resolved: beyond the slit the wavefronts have become genuine circular arcs centered on the slit opening itself (the asymmetric spreading noted at level 3 is no longer present), the transition from the point-source-centered arcs to the slit-centered arcs is smooth and unbroken (no gap or jump in the wave pattern as it crosses the barrier), and no other point on the barrier (e.g., an edge or corner) generates a competing set of ripples.
level_5: Everything required for score 4 is shown, and in addition the slit-centered ripples shrink in height steadily with distance from the slit (no sudden brightening, clipping, or flat plateau in ripple height), no crossing fringe pattern or standing-wave pattern appears anywhere in the tank (which would indicate two-slit interference or unwanted reflections), and the ripple motion is smooth and unbroken from the moment the source activates to the end of the clip, fully consistent with textbook single-slit water-wave diffraction.

Spatiotemporal Consistency rubric:
level_1: The barrier, slit, or point source appears or disappears between frames; the point source jumps to a new location in the tank; ripples skip across empty space with no wavefront connecting their origin to their current position; the overall lighting on the water surface swings abruptly from bright to dark (or vice versa) with no visible cause; or the whole scene cuts to a visibly different camera angle mid-sequence.
level_2: Objects stay present but behave inconsistently: the barrier's thickness or the slit's width visibly changes from one frame to the next without explanation, the water surface flickers between distinct textures, or the point source's ripple ring briefly freezes and then jumps ahead instead of expanding smoothly.
level_3: The tank, barrier, slit, and point source stay fixed in position and shape throughout; ripples expand and cross the slit with continuous, unbroken motion; the shadow cast by the barrier onto the tank floor stays anchored directly beneath the barrier's own footprint rather than drifting sideways as ripples pass beneath it; minor artifacts such as a brief shimmer on the water surface unrelated to the ripples are tolerated.
level_4: Everything required for score 3 holds, and in addition the overhead camera view stays perfectly fixed with no pan, tilt, or zoom; the water's surface keeps a consistent glassy reflectivity across the whole tank; the barrier and slit keep sharp, unbroken outlines the entire time; and the ripple pattern shows no visible gap or freeze as it crosses from one side of the barrier to the other.
level_5: Everything required for score 4 holds, and in addition the ripple crests move frame to frame at a steady, physically plausible pace (no sudden sliding, stretching, or skipped frames); the barrier never appears to float above or sink below the ripples passing near it; ripples are never rendered as if passing in front of the barrier when they should be blocked by it; and the point source's surface glint stays fixed at the source's own location for the entire clip rather than drifting toward the slit or the tank walls.