Domain: Natural Science — Physics
Target concept: A white light beam passes through a glass prism and is decomposed into a rainbow.

Video generation prompt: A narrow beam of white light is directed through a transparent triangular glass prism onto a wall or screen. While keeping the position of the light beam fixed, slowly rotate the prism.

Evaluation guide:
(i) Target concept: Optical dispersion of polychromatic light via angle-dependent refraction in a dielectric wedge.
Minimum mechanism: Light must be polychromatic (white) and reasonably collimated; the prism must be triangular, transparent, and have a refractive index that varies with wavelength; as soon as the beam passes through the prism's two angled faces, it separates into a spectrum on the screen; this dispersion does not require any motion; rotating the prism changes the angle of incidence and therefore shifts and reshapes where the existing spectrum falls on the screen, and can change how spread out it is, but it does not switch dispersion on or off.
(ii)Storyline: Frame 0–2: Static setup: white beam aligned to prism center; a continuous rainbow band is already visible on the screen, in correct spectral order, before any rotation begins. Frame 3–7: Prism begins rotating: the rainbow band shifts position along the screen and its width/spread changes; spectral order remains invariant throughout. Frame 8–10: Rotation continues: the band stays fully formed, contiguous, and correctly ordered as it keeps moving/reshaping with the prism's orientation; no reversal, splitting, or fading; beam stays narrow and prism stays transparent. Perspective is fixed frontal view showing beam, prism, and screen in one plane; all elements fully visible and occlusion-free throughout.

Manual:
Experimental Procedure
1. Position a narrow collimated white light beam to strike the center of a transparent triangular glass prism.
2. Place a matte white wall or screen behind the prism to capture the transmitted light.
3. While keeping beam and screen fixed, rotate the prism slowly around its vertical axis.
Observation of Experimental Phenomena
A continuous, spatially ordered band of colors (red, orange, yellow, green, blue, violet) appears on the screen and shifts position smoothly as the prism rotates.
Summary of Experimental Principles
White light is composed of multiple wavelengths; different wavelengths refract by different amounts in glass (dispersion), causing separation into a visible spectrum when passing through a prism.

Prompt Grounding rubric:
level_1: No white light beam is visible, no triangular glass prism appears, no wall or screen is shown, no rotation takes place, and none of the three core elements (source, prism, screen) appear together.
level_2: At least one of the three core elements shows up (for instance the prism alone, or the screen alone), but the narrow white beam itself is missing, there is no visible line-up of source, prism, and screen, and the prism never rotates.
level_3: The white light source, the triangular glass prism, and the wall/screen are all present and arranged so the beam strikes the prism and projects onto the screen; the prism is rotated at some point in the video; however the rotation isn't clearly linked to any visible change on the screen, for example the prism turns but the pattern on screen looks the same throughout.
level_4: Everything at the 3-point level holds, and in addition the beam strikes the center of the prism, the prism keeps rotating for the whole video, the screen visibly shows the pattern changing, and there is no missing, duplicated, or wrong type of optic (no cylindrical lens, no colored filter substituting for the prism).
level_5: Everything at the 4-point level holds, and in addition the beam itself is visibly narrow (a single thin stream, not a wide diffuse cone), the prism's triangular cross-section is recognizable (two angled faces and a base visible from the side), the screen is flat and matte with no obvious glare, and the beam's origin and the screen both stay fixed in place while only the prism turns; no camera pan, zoom, or repositioning of any object.

Scientific and Causal Correctness rubric:
level_1: No spectral separation ever appears (the light on the screen stays white or a single color at every frame), or the color pattern doesn't respond at all to the prism's presence or orientation, as if the prism weren't affecting the beam.
level_2: A colored band appears, but the colors are out of their natural sequence (for instance violet above red when the beam's orientation calls for the opposite order), or the colors are jumbled/random rather than forming an ordered band, or the color appears in the wrong location relative to where the beam actually exits the prism.
level_3: A continuous band of colors is visible on the screen in the correct spectral order (red, orange, yellow, green, blue, violet along one axis) both before rotation starts and while the prism turns; however the band sometimes drops out or shows only a couple of colors in some frames, or its width/position doesn't track the prism's orientation the way refraction would predict.
level_4: The full red-to-violet sequence is visible and spatially contiguous in every frame, including the static opening frames before any rotation, and continues to be shown correctly as the prism turns; the band's position and spread shift smoothly and continuously as the prism rotates, always keeping the correct spectral order with no gaps, splits, or reversals; no non-spectral colors (pink, brown, or plain white patches) appear inside the band.
level_5: Everything at the 4-point level holds, and in addition the colored band is always one single contiguous region rather than a secondary or overlapping rainbow, its shape and orientation match what refraction through a triangular prism would produce (elongated across the beam's spread direction), there are no stray color fringes, halos, or oversaturated glow around its edges, and the hues read as a natural daylight spectrum rather than exaggerated or shifted colors (e.g. not a neon cyan standing in for blue).

Spatiotemporal Consistency rubric:
level_1: Severe breaks in continuity: an object jumps to a new position between frames, the prism's orientation or location changes discontinuously, the beam flickers on and off with no cause, the screen disappears and reappears, or the lighting changes abruptly with no connection to the prism's rotation.
level_2: The prism keeps rotating but its apex or base shifts sideways or up/down across frames as if it weren't spinning around a fixed point; the beam's origin drifts; the screen's surface appears to warp or change perspective partway through; or shadows fall in directions inconsistent with the light source and the prism's actual position.
level_3: Minor, easy-to-miss inconsistencies are allowed: a slight jitter in the beam's position, a small wobble in the prism's rotation axis, or a brief misalignment between where the beam enters the prism and the prism's face in one or two frames, but there is no larger structural break, just a bit of roughness in the motion.
level_4: Everything at the 3-point level holds, and in addition the beam consistently strikes the same spot on the prism's face, the prism spins around one fixed central axis without drifting sideways, the screen stays rigid and doesn't move, and the lighting/shadows change gradually and in a way that matches the prism's rotation rather than jumping erratically.
level_5: Everything at the 4-point level holds, and in addition the motion looks completely smooth with no stutter or sudden speed change, the beam's edge stays sharply defined throughout, the prism's faces catch the light consistently without sudden bright flares or going dark, the screen's surface and finish look the same in every frame, and there is no shift in perspective that would suggest the camera moved during the prism's rotation.