Domain: Natural Science — Physics
Target concept: Tyndall effect produced by laser illumination of a liquid

Video generation prompt: Take two transparent beakers, fill beaker A with distilled water, and place ferric hydroxide colloid in beaker B. Illuminate them from the side using a red laser pointer.

Evaluation guide:
(i) Target concept: Light scattering by colloidal particles under monochromatic side-illumination.
Minimum mechanism: Colloidal dispersion must contain suspended particles large enough to scatter visible light (1–100 nm), while solvent must be optically homogeneous at sub-colloidal scale; red laser provides coherent monochromatic source; side-view geometry enables observation of scattered light perpendicular to beam direction.
(ii)Storyline: [Frame 0–2] Two static beakers enter fixed side-by-side composition; [Frame 3–4] Red laser pointer activates and emits horizontal beam toward beaker sides at consistent height; [Frame 5–8] Beam contacts beaker A → no visible path; beam contacts beaker B → immediate appearance of continuous red-orange scattering column confined within liquid volume; [Frame 9] Both beakers remain in frame with unchanged spatial relationship and lighting; perspective is fixed frontal/side view enabling direct comparison; no occlusion of liquid volumes or beam paths at any point.

Manual:
Experimental Procedure
1. Place two identical transparent beakers side-by-side on a flat surface.
2. Fill beaker A with distilled water (colorless, clear liquid).
3. Fill beaker B with ferric hydroxide colloid (reddish-brown, translucent liquid).
4. Illuminate both beakers simultaneously from the side using a red laser pointer, keeping beam horizontal and at same height.
Observation of Experimental Phenomena
- In beaker A (distilled water): laser beam passes through invisibly — no visible light path.
- In beaker B (ferric hydroxide colloid): bright red-orange scattering column appears along beam path — clear Tyndall effect.
Summary of Experimental Principles
The Tyndall effect occurs when light is scattered by colloidal particles. Distilled water is a true solution with particle size <1 nm → no scattering. Ferric hydroxide colloid has particle size 1–100 nm → strong scattering of red laser light, making beam path visible.

Prompt Grounding rubric:
level_1: No beakers appear, or only one beaker is shown, or the beakers used are opaque rather than transparent, or no red laser pointer appears anywhere, or no side-illumination action is shown, or the liquids are never actually placed inside the beakers (e.g., poured mid-air with no container to receive them).
level_2: Two transparent beakers sit side by side, but at least one of the following is wrong: beaker A does not read as a colorless, clear liquid; beaker B does not read as a reddish-brown, translucent liquid; no red laser pointer is visibly held or positioned near the beakers; or the laser is never aimed horizontally at the side of either beaker.
level_3: Two transparent, side-by-side beakers hold the correct liquids (a colorless clear liquid in beaker A and a reddish-brown translucent liquid in beaker B), and a red laser pointer is visibly aimed to send a horizontal beam toward the side of both beakers, with the illumination action clearly shown; nothing else (a dropper, a hand, a label) blocks the view of either beaker during this.
level_4: Everything described for a 3 is true, and in addition the laser beam is visibly unbroken from the pointer to the point where it meets each beaker's glass, both beakers stay completely still throughout the illumination, neither beaker's base or side is blocked by a hand or tool at the moment of contact, and the two beakers keep the same spacing and alignment relative to each other with no cut or camera repositioning between them.
level_5: Building on everything required for a 4, the beam meets both beakers at the same height relative to their rims, both beakers stay in a clear, unobstructed side view for the entire clip, neither beaker's shape nor the liquid's surface flickers, warps, or otherwise breaks its visual identity, and the beam itself never appears to skip or reset partway through the clip.

Scientific and Causal Correctness rubric:
level_1: Neither beaker shows any sign of the Tyndall effect, or both beakers show the same scattering behavior (both bright or both dark), or a scattering column appears in beaker A (distilled water) instead of or in addition to beaker B, or any scattering that does appear in beaker B is not red-orange.
level_2: A scattering effect shows up in only one beaker, but something about it is scientifically wrong: it appears in beaker A rather than B, or in beaker B the beam only produces a bright spot where it exits the glass with no visible glowing path through the liquid, or the scattering color in beaker B reads as white or blue rather than red-orange.
level_3: A clearly visible, red-orange glowing path runs along the laser's path through beaker B only, with no equivalent scattering visible anywhere in beaker A; the beam enters and exits both beakers in a straight line without bending.
level_4: Everything described for a 3 is true, and in addition the glowing path in beaker B stays confined within the liquid itself (it doesn't extend up into the air above the liquid or below it), beaker A shows no scattering even where the beam meets the liquid surface, the beam stays straight through both liquids, and the scattering color reads as a true red-orange rather than yellow or pink.
level_5: Building on everything required for a 4, the glowing path in beaker B has a sharp, well-defined edge rather than a soft halo bleeding into the surrounding glass or air, it looks brightest along the beam's center and fades gradually outward, beaker A still shows no trace of scattering at the same viewing angle and distance, and the glow in beaker B neither appears late nor fades out at any point once the beam is switched on.

Spatiotemporal Consistency rubric:
level_1: One or both beakers vanish and reappear or jump to a different spot on screen between frames; the laser beam's origin or direction jumps with no visible motion connecting the two positions; beaker B's color or transparency changes abruptly partway through the clip; the camera cuts suddenly to a different view; or the ambient room lighting disappears and comes back.
level_2: At least one clear spatiotemporal problem is visible: the two beakers shift position relative to each other (sliding, rotating, or changing size) without any shown cause, the laser beam's position or angle changes abruptly rather than smoothly, reflections or shadows on the beakers flicker or flip direction inconsistently, or the liquid surface ripples in a way that defies gravity (e.g., waves appearing to move upward on their own).
level_3: The two beakers stay in the same relative position and orientation, and the laser pointer either stays still or moves with a smooth, continuous path; the beam keeps a steady thickness and alignment throughout; the liquid surfaces stay essentially calm or show only very mild, even ripples; the overall lighting on the scene stays even and matches a single, consistent light source across the clip.
level_4: Everything described for a 3 is true, and in addition neither beaker's shape warps, bends, or changes transparency at any point, there is no visible jitter or stutter in the beakers or beam, the beaker edges stay visually consistent with the background behind them if the camera moves at all, and nothing enters the frame (such as a hand) without also visibly leaving it.
level_5: Building on everything required for a 4, the beaker rims, the liquid surfaces, and the beam's path all look like one continuous, stable scene from start to finish with no visible drift or misalignment, motion blur is not present on parts of the scene that are supposed to be still, the sense of which objects sit in front of others stays consistent throughout, and the beaker edges show no warping or bending typical of a distorted lens.