Domain: Natural Science — Physics
Target concept: Comparison of Refractive Indices of Different Media (such as Water and Oil)

Video generation prompt: Take two identical glass cups, fill one with clear water and the other with cooking oil, insert the same wooden stick into both, and observe from the side.

Evaluation guide:
(i) Target concept: Refractive index governs apparent lateral displacement of submerged objects at air-liquid interfaces.
Minimum mechanism: Light must travel from air → liquid → air to observer; interface must be planar and still; observer must be at oblique angle (side view) to resolve lateral shift; liquids must be transparent and immiscible with wood; wooden stick must be opaque enough to trace visual continuity across interface.
(ii)Storyline: [Frame 0] Two identical empty glass cups placed adjacent on neutral background. → [Frame 1–2] Cups filled sequentially (water first, oil second) with no spillage or overflow. → [Frame 3–4] Identical wooden sticks inserted vertically and simultaneously into each cup to identical depth. → [Frame 5–10] Fixed side-view shot holds steady; observer sees continuous, unbroken stick in both cups, with submerged portions visibly offset horizontally at liquid surface; offset larger in oil cup. No hand presence after insertion; no motion beyond natural settling. Visibility constraint: entire stick length above and below surface must be fully visible in both cups; no occlusion by cup rim or finger.

Manual:
Experimental Procedure
1. Place two identical transparent glass cups side-by-side on a flat surface.
2. Fill left cup with clear water; fill right cup with cooking oil.
3. Insert identical wooden stick vertically into each cup until submerged to same depth.
4. Observe both cups simultaneously from a fixed side viewpoint.
Observation of Experimental Phenomena
The submerged portion of the wooden stick appears laterally displaced at the liquid-air interface in both cups; the displacement is visibly greater in the oil-filled cup than in the water-filled cup.
Summary of Experimental Principles
Light travels slower in media with higher refractive index; cooking oil has a higher refractive index (~1.47) than water (~1.33), causing greater bending (refraction) of light rays at the interface, resulting in larger apparent lateral shift of submerged objects.

Prompt Grounding rubric:
level_1: Fewer than two glass cups appear on screen, or none of the visible cups contains clear water, or none contains cooking oil, or no wooden stick is inserted into either cup.
level_2: Two glass cups are shown, but they are noticeably different from each other in shape or size, or a wooden stick is inserted into only one of the two cups, or the liquid in at least one cup cannot be identified as either water or oil: for example it looks cloudy, colored, or otherwise unclear.
level_3: Two matching transparent glass cups stand side by side; one contains a clear, colorless liquid (water) and the other a pale yellow liquid (cooking oil); one wooden stick of the same kind is inserted straight down into each cup to roughly the same depth; the camera holds a fixed side-on view showing both cups at once.
level_4: Two matching glass cups stand side by side holding water and cooking oil as described above, each with a matching wooden stick inserted to the same depth, viewed from a fixed side angle; in addition, both sticks stay still for the entire clip, both liquids stay clear with no bubbles, swirling, or surface waves, no hand or other object blocks the view of either cup or stick, and both cups stay upright and stationary throughout.
level_5: Two matching glass cups stand side by side, one holding clear water and the other pale yellow cooking oil, each with a matching wooden stick inserted to the same depth, viewed from a fixed side angle, with both sticks motionless, both liquids clear and undisturbed, and no hand or object blocking the view; in addition, each liquid surface shows a naturally curved meniscus where it meets the glass, the wooden stick in each cup keeps a consistent, undistorted shape with no visible warping of the wood itself, and the footage has no motion blur, dropped frames, or rendering glitches around either cup, stick, or liquid. Whether the two liquids' optical behavior actually differs from one another is a separate judgment, not scored here.

Scientific and Causal Correctness rubric:
level_1: Both sticks look completely straight in their cups with no visible shift at the liquid surface, so no difference between water and oil is visible; or the stick in the oil cup shows less sideways shift at the surface than the stick in the water cup, the opposite of what should happen.
level_2: A sideways shift at the liquid surface is visible in at least one cup, but something about it is wrong: for example both sticks appear to bend in the same direction relative to the cups' centerlines instead of each showing its own offset, or the stick in the water cup shows a greater sideways shift than the stick in the oil cup (the reverse of the expected relationship), or the stick looks broken into two disconnected pieces at the surface rather than remaining one continuous piece.
level_3: The stick in the water cup shows a visible sideways shift of its submerged part at the liquid surface; the stick in the oil cup shows a larger sideways shift at the same kind of surface; this shift appears right at the liquid surface in both cups, not somewhere else along the stick; and in both cups the stick remains one continuous piece with no visible break or gap at the interface.
level_4: The stick in the water cup shows a visible sideways shift at the surface, and the stick in the oil cup shows a clearly larger shift than the one in water, large enough to see at a glance rather than a subtle or marginal difference; there is no flickering or shimmering at either interface that would suggest an unstable effect rather than a steady one; and both liquids stay clear enough that the submerged part of each stick remains fully visible.
level_5: The stick in the water cup shows a visible sideways shift at the surface, and the stick in the oil cup shows a clearly larger shift, matching what is expected because cooking oil bends light more than water does; the submerged part of each stick keeps a consistent thickness and sharp edges in both liquids, with no colored fringing at either interface; and nothing in the footage looks like a rendering artifact or optical trick standing in for real refraction; the effect looks like a natural consequence of the two liquids' properties.

Spatiotemporal Consistency rubric:
level_1: The cups appear to jump to new positions between shots instead of staying in one continuous take; the stick in either cup drops out of view for a stretch of the clip and then shows up again with no visible reason; the liquid level in either cup changes abruptly with no visible cause; the camera view switches, for example from side-on to overhead and back, without any smooth transition; or the scene's overall brightness suddenly jumps between light and dark with no in-scene cause.
level_2: One or both cups visibly tilt or rotate by more than about 10 degrees partway through the clip; a stick wobbles back and forth or spins around its own axis instead of staying still; the liquid surface ripples, sloshes, or visibly flows rather than sitting still; or the bright highlight on a cup's glass surface suddenly jumps to a different spot with no matching change in the camera view or lighting.
level_3: Both cups stay in the same position and orientation throughout; both sticks remain upright and still; both liquid surfaces stay flat and undisturbed with no ripples or waves; the bright highlight or reflection visible on each cup's curved glass surface stays in roughly the same spot rather than sliding around as if the camera or a light were moving; and neither cup nor stick appears clipped, warped, or geometrically distorted.
level_4: Both cups stay in the same position and orientation throughout, both sticks remain upright and still, both liquid surfaces stay flat and undisturbed, and the highlight on each cup's glass surface stays in roughly the same spot without sliding around; in addition, motion between frames looks smooth with no visible strobing or sudden micro-jumps, the rims and edges of both cups stay crisp and continuous without softening or breaking up, the sticks hold a steady, unchanging position and angle in their cups from start to finish, and the background behind the cups shows no sideways drift that would suggest unwanted camera movement.
level_5: Both cups stay fixed in position and orientation, both sticks stay upright and still, both liquid surfaces stay flat, the glass highlights stay put, and motion between frames is smooth with steady cup edges and stick alignment throughout, as described above; in addition, the pacing of the whole clip feels even, with no odd speeding-up or slowing-down of what should be a static scene; playback shows no visible stutter or skipped-looking motion in the stick or cup edges; the near cup never overlaps the far cup in a way that looks physically wrong; and the background stays static and unobtrusive throughout.