Domain: Natural Science — Physics
Target concept: Visible Light Spectrum Color Mixing Experiment (Green + Blue)

Video generation prompt: Take the green and blue laser sources, adjust the optical path so that the two beams overlap on a white screen, and observe the color in the overlapping region.

Evaluation guide:
(i) Target concept: Additive color mixing of monochromatic visible light sources (green + blue → cyan).
Minimum mechanism: Two spatially coherent, spectrally narrowband light sources (green ~532 nm, blue ~450 nm) must simultaneously illuminate the same diffusing surface (white screen) with sufficient overlap area and intensity to trigger human photoreceptor summation yielding cyan perception.
(ii)Storyline: [Frame 1–3] Green laser dot appears on left side of white screen; [Frame 4–6] Blue laser dot appears on right side of same screen; [Frame 7–8] Both dots move toward center while maintaining shape and brightness; [Frame 9] Dots fully coincide → single cyan region appears instantly; [Frame 10] Cyan region persists uniformly, flanked by unchanged green and blue margins. Perspective: fixed frontal view; screen fills ≥60% of frame height; lasers are partially visible (emission apertures or housings shown); no occlusion of overlap region at any time.

Manual:
Experimental Procedure
1. Position green and blue laser pointers so their beams project onto the same white screen.
2. Adjust the angles of both lasers until their beams converge and fully overlap on the screen.
Observation of Experimental Phenomena
In the overlapping region, a uniform cyan color appears — distinctly different from the green-only and blue-only regions.
Summary of Experimental Principles
Green and blue light are additive primaries; when combined at equal intensity, they produce cyan via additive color mixing in the visible light spectrum.

Prompt Grounding rubric:
level_1: No green laser source is shown, no blue laser source is shown, no white screen is shown, or no beam from either laser ever reaches the screen at all.
level_2: Only one of the two lasers (green or blue) is visible projecting a beam onto the white screen; the second laser or its beam never appears, so no overlap region can ever form.
level_3: Both the green and blue lasers are visible and both beams land on the same white screen, but the two beam spots stay fully separated from each other (side by side with a visible gap) for the whole clip: they never touch or converge.
level_4: Both lasers and their housings/apertures are visible, both beams land on the same white screen, and the beams move toward each other and their edges touch or partially overlap at some point in the clip; but the resulting shared region is small, partial, or unevenly bounded (regardless of what color it shows).
level_5: Both laser housings and beams remain visible throughout, the screen fills a large, clearly framed portion of the shot, and the two beams fully converge into one single, cleanly bounded overlap region flanked by a clearly separate green-only patch and blue-only patch; the overlap's shape and boundary are unambiguous (independent of the color judged elsewhere).

Scientific and Causal Correctness rubric:
level_1: There is no visible link between the beams touching and any color change: either no overlap region ever appears, or the overlap area shows the same color as one of the input beams, or it shows a color additive mixing cannot produce (e.g., red, yellow, magenta, black, or white).
level_2: An overlap area exists but its color contradicts additive mixing of green and blue light (e.g., it looks yellow, purple, or black), or only one of the two input colors shows through with no blending at all.
level_3: The overlap area shows a color visibly different from both the pure green and pure blue beam colors, and the hue is a plausible blend (something bluish-green or greenish-blue), but it lacks the saturated, spectrally pure look of true cyan: e.g., it reads as washed-out, grayish, or too dark/light to read clearly as cyan.
level_4: The overlap area shows a clear cyan color, directly bordered by a pure green patch on one side and a pure blue patch on the other, with no stray colors (no yellow fringe, white halo, or magenta bleed) visible in or around the overlap.
level_5: The overlap area shows a uniform, vivid, saturated cyan with no gradient or patchiness, directly flanked by a pure green region and a pure blue region with sharp, clean boundaries; no color bleeding, haze, or fringing appears anywhere on the screen.

Spatiotemporal Consistency rubric:
level_1: One or both beams jump to a new spot on the screen without visibly traveling there; the screen or a laser blinks on/off abruptly; a beam's shape changes suddenly (e.g., a dot becomes a line) with no visible cause; or the room lighting flips abruptly between frames.
level_2: A beam visibly breaks apart, vanishes partway along its path, or shows a sharp kink instead of a straight line; the screen surface appears to warp or bend; the beam brightness pulses on and off instead of changing smoothly; or a beam appears disconnected from its laser source, floating without a visible origin.
level_3: Both beams travel in continuous, unbroken paths from their lasers to the screen; each beam keeps a stable shape (a clean dot or line) throughout; the screen stays flat and stationary; the overall brightness of the scene stays even, with no unexplained flicker on the screen, beams, or laser housings.
level_4: Both beams do everything described for a 3, and in addition the two beams visibly approach and converge smoothly (with no sudden jump-cut at the moment of contact), and the shared overlap region grows continuously as the beams come together, matching the pace of the beams' motion.
level_5: Both beams do everything described for a 4, and in addition the two beams reach full alignment in the same instant, with the overlap region appearing uniformly right when the beams coincide (no fade-in or delay), and the beams hold rock-steady relative positions with no visible drifting or wobble for the rest of the clip.