Domain: Natural Science — Biophysics
Target concept: Pollen particles in water exhibit jittery motion under an optical microscope.

Video generation prompt: A light microscope records pollen particles suspended in still water on a glass slide, held at a fixed camera angle and magnification for an extended recording.

Evaluation guide:
(i) Target concept: Brownian motion of colloidal pollen particles in quiescent aqueous medium under optical microscopy.
Minimum mechanism: Water must be macroscopically still (no convection), particles must be neutrally buoyant and non-motile (not self-propelled; pollen is biological material, but it must not swim or move under its own power the way a motile microorganism would), and thermal energy must drive stochastic collisions, with no external agitation, electric fields, or chemical gradients.
(ii)Storyline: [Frame 0] Static microscope view centered on water layer on glass slide, showing clear boundaries and multiple stationary-looking pollen specks. → [Early frames] Individual specks begin independent, erratic positional shifts, with no shared timing or direction. → [Mid-sequence] All specks continue jittering heterogeneously; no speck exits water layer or slides along interface; water remains optically homogeneous. → [Late frames] Jitter persists without attenuation or synchronization; slide edges and field-of-view remain geometrically invariant. → Visibility constraint: Only in-focus plane is sharp; out-of-focus regions show natural blur; no particle detail beyond diffraction limit is rendered.

Manual:
Experimental Procedure
1. Place a drop of still water containing suspended pollen particles onto a clean glass slide.
2. Cover gently with a coverslip to prevent evaporation and stabilize water layer.
3. Mount slide on light microscope stage and focus on water layer at medium magnification.
4. Record video at fixed magnification and viewpoint for 10 seconds.
Observation of Experimental Phenomena
Multiple small, brownish pollen particles undergo continuous, random, short-distance jittery motion within the water layer — no net drift, no synchronization, no directional flow.
Summary of Experimental Principles
Pollen particles in water exhibit Brownian motion due to unequal bombardment by water molecules — a direct microscopic manifestation of molecular kinetic energy and thermodynamic randomness.

Prompt Grounding rubric:
level_1: No optical microscope framing, no glass slide, no water droplet, and no pollen-like specks are visible; or the scene is outdoors, macro-scale, or shows an unrelated process (e.g., cells dividing, dust floating in air, liquid boiling). None of the posted_prompt's setup elements are present.
level_2: At least one correct setup element is present (glass slide, water layer, or pollen-like specks) but the microscope framing, fixed camera angle, or still-water context is missing; e.g., specks appear to float in open air, sit on a dry slide, or the view resembles an electron-microscope render rather than a light-microscope field.
level_3: A circular, vignette-edged microscope field-of-view is shown; a flat glass slide holding a uniform water layer is clearly identifiable; several small brown/tan pollen-like specks sit within the water; the camera angle and magnification are fixed and held steady, whether or not the specks show any positional change frame to frame.
level_4: All elements of score 3 are present, and every visible speck shows some independent positional change across the clip (not all frozen in place); the microscope framing itself stays fixed (no pan, zoom, or rotation of the field-of-view), and the slide edges and water layer keep the same visible extent throughout.
level_5: All elements of score 4 are present, and each pollen speck shows visible positional change for the full duration of the clip rather than only in isolated moments; the glass slide, coverslip edge (if shown), and circular field-of-view boundary remain visibly unchanged in position and shape from the first frame to the last.

Scientific and Causal Correctness rubric:
level_1: Phenomenon contradicts Brownian motion: pollen specks travel in straight lines, accelerate uniformly, rotate in place, arrange into patterns, or lurch as if pushed by an invisible force; or the water appears turbulent, boiling, or flowing; or specks are absent while the video implies motion is occurring.
level_2: Specks move, but show exactly one non-physical behavior: all specks drift together in the same direction (implying convection or a current), all start/stop moving in unison (implying an external vibration trigger), motion only begins after an implied external stimulus (tap, shake, flash) not present in the setup, or the specks are the wrong color (e.g., neon green, metallic silver) or wrong size (larger than a visible slide scratch, or covering more than roughly 10% of the frame).
level_3: Specks are correctly sized (tiny, sub-millimeter), correctly colored (brown/tan, consistent with dried pollen), and stay within the water layer; motion is present and non-uniform but shows at least one flaw: sustained directional drift across several consecutive frames, two or more specks tracing the same path in lockstep, or all motion pausing for a full second or more.
level_4: Every speck is correctly sized, colored, and confined to the water; motion is exclusively small-scale jitter with no net displacement, no shared timing between specks, and no flow pattern; no speck crosses the slide boundary or leaves the water layer; no speck shows self-propelled locomotion (e.g., a whip-like flagellum or amoeboid shape change); the water itself stays optically calm, with no ripples, shimmer, or heat-shimmer distortion.
level_5: All conditions of score 4 hold, and each speck's jitter is demonstrably independent: no two specks share a matching trajectory segment lasting more than an instant, no correlated pausing or resuming, and no shared burst of speed; jitter amplitude clearly differs from speck to speck without repeating in a fixed cycle; the water layer shows no visible gradient, meniscus distortion, or evaporation marks; pollen color stays a matte brown/tan with no gloss or glow.

Spatiotemporal Consistency rubric:
level_1: Severe spatiotemporal rupture: the water droplet or glass slide changes shape, size, or position abruptly between frames; pollen specks blink in and out of existence; the circular microscope field-of-view suddenly re-centers, rotates, or zooms; the frame rate drops so much that the specks' motion becomes disconnected jumps instead of continuous jitter; or the lighting shifts abruptly between adjacent frames (e.g., a bright field-of-view suddenly going dark with no visible cause).
level_2: Moderate discontinuities: more than two pollen specks vanish and reappear across consecutive frames; the slide or coverslip edge visibly wobbles or flickers; the water layer's apparent brightness or thickness shifts inconsistently between frames; at least one speck's position jumps to more than twice its typical jitter amplitude in a single frame, reading as an obvious skip rather than jitter; or the background outside the water layer abruptly changes color or texture between frames.
level_3: Minor but noticeable flaws: at most one pollen speck disappears and reappears once during the clip; the slide or coverslip edge shows a faint shimmer but stays straight; the illuminated field-of-view holds a roughly steady brightness with only slight, non-distracting flicker near its circular edge; jitter motion is mostly continuous, with no more than one abrupt repositioning per speck.
level_4: Every pollen speck and the slide/coverslip stay in a fixed relative position within the frame: no speck drifts to a new average location, none merge or split, none change size; the microscope's condenser illumination lighting the water layer holds a steady brightness and color cast for the whole clip; the circular field-of-view boundary neither drifts sideways nor changes size.
level_5: The glass slide and coverslip edges stay visibly stationary and undistorted for the entire clip; the water layer's optical clarity (no added flare, fogging, or color fringing) and the field-of-view's illumination stay unchanged in brightness and color from the first frame to the last; every pollen speck's jitter path can be followed continuously frame to frame, with no sudden repositioning, no ghosting/doubling, and no camera parallax or focus breathing.