Domain: Natural Science — Physics
Target concept: Siphon Phenomenon Demonstration

Video generation prompt: Take two beakers, fill beaker A (located at a higher position) with red water, and keep beaker B (located at a lower position) empty; then fill a rubber tube with water and insert both ends of the tube into the two beakers.

Evaluation guide:
(i) Target concept: Siphon-driven unidirectional liquid transfer enabled by atmospheric pressure differential and gravitational potential energy difference between two reservoirs at different heights.
Minimum mechanism: Continuous liquid column inside tube; hydrostatic pressure at higher-elevation inlet > pressure at lower-elevation outlet; tube apex must be above liquid level in source but below source rim; no air ingress breaking column continuity.
(ii)Storyline: Frame 0–1: Static setup, Beaker A (high) full of red water, Beaker B (low) empty, tube pre-filled and held ready. Frame 2–3: Tube ends inserted, both submerged, no spillage. Frame 4–8: Continuous red water flow from A→B through tube; liquid levels change monotonically; tube remains fully occupied. Frame 9: Flow ongoing, no reversal, no stoppage, no break. Perspective: Fixed frontal view, full-beaker framing, no occlusion, consistent lighting, top-down height distinction visually unambiguous.

Manual:
Experimental Procedure
1. Place two identical glass beakers: Beaker A higher, Beaker B lower, aligned vertically.
2. Fill Beaker A with red water; leave Beaker B empty.
3. Fill a flexible rubber tube completely with water; insert one end into Beaker A (submerged), other end into Beaker B (submerged).
Observation of Experimental Phenomena
Red water flows continuously from Beaker A through the tube into Beaker B; level in Beaker A drops, level in Beaker B rises; flow stops if tube is lifted or broken.
Summary of Experimental Principles
Siphon phenomenon: Liquid flows from higher to lower elevation through an intermediate elevated path due to atmospheric pressure and gravity acting on unequal liquid columns.

Prompt Grounding rubric:
level_1: Two beakers are not both shown, no rubber tube is visible, red water is absent, the two beakers are not shown at different heights, or the tube's ends are never inserted into either beaker.
level_2: Two beakers appear side by side but at the same height with no visible elevation difference; the rubber tube is present but is empty of water, or only one end (or neither end) sits inside a beaker; or red water is present in only one beaker with the tube never touching it.
level_3: Two beakers are shown at clearly different heights, with the higher beaker (Beaker A) full of red water and the lower beaker (Beaker B) empty; a rubber tube filled with water has both ends inserted into the two beakers, matching the posted setup with no missing or substituted parts.
level_4: Everything required for score 3 is shown, and in addition both tube ends are clearly submerged below the liquid or air surface of their respective beakers with no end floating loose or only partly dipped, and the two beakers stay at their original heights throughout the video without being moved or tilted.
level_5: Everything required for score 4 is shown, and in addition the red water stays confined to Beaker A at the very start with no water already present in Beaker B before the tube begins working, the tube stays seated in both beakers without slipping out or kinking, and no hand, label, or stand blocks the view of the beakers or tube.

Scientific and Causal Correctness rubric:
level_1: No liquid transfer is visible at all; red water appears in both beakers simultaneously from the first frame; the tube shows no water inside it, or contains a visible air gap that would block continuous flow; or the water appears to move upward from the lower beaker into the higher one.
level_2: Red water appears in Beaker B before the tube is ever shown making contact with both beakers; the tube is dry or only partly filled with water when flow supposedly begins; or the red color visibly fades or dilutes as it travels, which is inconsistent with a plain water transfer.
level_3: Red water flows continuously from Beaker A into Beaker B through the tube only after both tube ends are inserted; the flow does not reverse or pause partway through; the level in Beaker A drops while the level in Beaker B rises; and the water stays a consistent red color throughout the transfer.
level_4: Everything required for score 3 holds, and in addition the flow is visibly continuous with no drips, gaps, or on-and-off spurts, and the water column inside the tube stays fully connected end to end with no air gap forming anywhere along its visible length while the flow runs.
level_5: Everything required for score 4 holds, and in addition the rate at which Beaker B fills looks physically reasonable rather than instantaneous, the transferred water stays clear with no cloudiness or turbidity, and the red water enters Beaker B without splashing over its rim or spilling to the side.

Spatiotemporal Consistency rubric:
level_1: Beaker A or Beaker B vanishes from the frame and then reappears; the rubber tube disappears and then reappears with no explanation; the scene lighting jumps from shadowed to bright within a single cut; either beaker's shape warps or stretches; or the camera cuts to a different angle with no transition.
level_2: One beaker shifts sideways or vertically partway through the video with no visible cause; the tube suddenly kinks sharply and then straightens out again in the very next frame; the red water's surface jitters or ripples with no corresponding cause; or the light reflecting off a beaker's surface changes brightness or position with no matching change elsewhere in the scene.
level_3: Both beakers keep the same size, shape, and position relative to each other throughout; the tube stays visible in the same place without dropping out of view or reappearing; the lighting on the beakers and tube looks the same from start to finish; and the flowing water moves smoothly without stutters or jumps.
level_4: Everything required for score 3 holds, and in addition the curve of the liquid surface where it meets each beaker's wall changes smoothly as the levels rise and fall rather than snapping flat or inverting, and the tube keeps the same width and curvature along its length throughout the flow.
level_5: Everything required for score 4 holds, and in addition the relative spacing between the beakers, the tube, and any background elements stays constant with no sudden shift in depth, the blur on the flowing water looks consistent with its visible speed and direction, and the video shows no repeated or skipped frames anywhere in the sequence.