Domain: Natural Science — Physics
Target concept: A soap film illuminated by white light exhibits varying colored fringes.

Video generation prompt: A vertical soap film is formed on a rectangular metal frame, illuminated by stable white light, while the soap film flows slowly and the frame is gently tilted.

Evaluation guide:
(i) Target concept: Thin-film interference in a gravity-draining vertical soap film under white light, where tilt modulates the thickness gradient and thus the spatial frequency and chromatic signature of interference fringes.
Minimum mechanism: Film must be a continuous, semi-transparent liquid lamella with non-uniform thickness (thicker at bottom); incident white light must be polychromatic and coherent enough to produce stable interference; viewing angle must be approximately perpendicular to film surface to resolve fringes.
(ii)Storyline: [Start] Vertical frame with intact, continuous soap film illuminated by stable white light → [Phase 1] Horizontal colored fringes emerge across full film width → [Phase 2] Fringes shift downward continuously as film drains (flow visible as smooth band motion) → [Phase 3] Frame begins gentle, monotonic tilt → [Phase 4] During tilt, fringes remain horizontal but increase in density (narrower spacing) and/or exhibit systematic hue redistribution (e.g., red-dominated region migrates) → [Visibility constraint] All events occur within a fixed frontal viewpoint; film must remain fully visible and unruptured; no occlusion, no camera motion, no lighting interruption.

Manual:
Experimental Procedure
1. A rectangular metal frame is held vertically.
2. A soap film is formed to fully span the frame.
3. Stable white light illuminates the film from the front.
4. Film flows slowly downward due to gravity.
5. Frame is gently tilted while observing.
Observation of Experimental Phenomena
Horizontal colored interference fringes appear across the soap film; fringe positions shift downward as film flows; fringe spacing and/or dominant colors change systematically as the frame tilts.
Summary of Experimental Principles
White light interference in a thin, wedge-shaped soap film: varying film thickness causes wavelength-dependent constructive/destructive interference, producing colored fringes; tilt alters the thickness gradient, changing fringe density and hue distribution.

Prompt Grounding rubric:
level_1: No rectangular frame holding a soap film is shown, or no soap film is present at all, or the illumination is not a steady white-light source (e.g., it is colored, flickering, or absent), or the frame never tilts, or the frame's vertical orientation is never established.
level_2: A rectangular frame holding a film-like sheet appears, but it is not clearly held vertically, or the film reads as a uniform, non-flowing sheet with no visible drainage or fringe motion; the white light is replaced by a colored or point-source light; the frame never visibly tilts.
level_3: A vertical rectangular frame holds a continuous, intact soap film spanning its full width; a steady white light illuminates the film from the front; the frame stays level with no tilt, and the film is shown without any obvious downward flow.
level_4: All level-3 requirements are met, and additionally: the film visibly drains downward over time, seen as interference bands or bright streaks sliding slowly down its surface; the frame then begins a gentle tilt that is visibly under way (its orientation is clearly changing) while staying at a small angle and without rupturing the film.
level_5: All level-4 requirements are met, and additionally: the frame is clearly vertical with the film spanning it edge-to-edge and intact from the very first frame; the white light is even across the film with no glare hot-spot or strong directional shadow; the film's downward drainage is continuous throughout; the tilt proceeds smoothly in one direction from vertical toward a slight incline, without pausing, reversing, or jumping.

Scientific and Causal Correctness rubric:
level_1: No colored interference fringes appear anywhere on the film; the film looks uniformly clear, grey, or a single flat color; its appearance does not change as the film drains or as the frame tilts.
level_2: Some color appears on the film, but only as scattered blotches rather than roughly horizontal bands; the coloring does not respond to the film's drainage or to the frame's tilt; there is no repeating, band-like structure.
level_3: Roughly horizontal colored fringes stretch across most of the film's width; the fringe colors vary from top to bottom of the film (for example, cooler blue/violet tones nearer the top and warmer red/orange tones nearer the bottom), but the fringes stay in place and do not visibly shift as the film drains or as the frame tilts.
level_4: All level-3 requirements are met, and additionally: the fringe pattern visibly slides downward as the film drains; once the tilt begins, either the fringe spacing visibly narrows or widens, or the dominant fringe color visibly shifts across the film; at least one of these two responses to tilt is clearly seen.
level_5: All level-4 requirements are met, and additionally: the fringes stay horizontal and slide downward in step with the film's visible drainage; during the tilt, the fringes both pack closer together and show a progressive top-to-bottom color shift across the film's surface; the fringe pattern changes smoothly, with no sudden jump or reversal in its behavior.

Spatiotemporal Consistency rubric:
level_1: The frame or the film abruptly appears or disappears partway through the shot; the film visibly ruptures and then reforms; the illumination switches on/off or changes color instantaneously; the camera itself jumps, rotates, or zooms; the film shows an impossible deformation, such as folding or tearing, that drainage alone would not produce.
level_2: The film's fringes move in obvious discrete jumps rather than a continuous drift; the frame's tilt happens as one abrupt rotation rather than a gradual change in orientation; the light's brightness or direction changes in a visible step rather than smoothly; the film's edges bulge or warp in a way that gravity-driven drainage would not produce.
level_3: The film drains downward with smooth, unbroken motion throughout; the frame holds its position and only its tilt angle changes; the white illumination stays steady in both brightness and direction; the film shows no rupture, hole, or structural break at any point, and the camera viewpoint never changes.
level_4: All level-3 requirements are met, and additionally: the frame's tilt is smooth and always progresses in the same direction, with no visible wobble or shake; the illumination stays even and steady; the film stays fully within the frame at every moment, and the fringes stay aligned with the film's visible surface rather than appearing to float off it.
level_5: All level-4 requirements are met, and additionally: the film's downward drainage looks smooth and even, without visible turbulence, ripples, or eddies disrupting it; the tilt keeps a steady, unbroken rate of rotation from start to finish; the lighting remains visually stable with no perceptible flicker or hue shift; the film shows no visible holes, tears, or rupture forming anywhere on its surface throughout the shot.