Domain: Natural Science — Physics
Target concept: Place a wooden block into a cup filled with water and add small stones, verifying that the water level rises slowly while the submerged volume of the wooden block remains unchanged.

Video generation prompt: Place a transparent cup filled with water on the table. Gently place a wooden block into the water so that it floats. Then add small stones one by one into the cup. Keep the wooden block floating freely without letting it touch the walls of the cup.

Evaluation guide:
(i) Target concept: Archimedes" principle applied to a floating object in a confined liquid system where added mass increases system weight but not the floating object"s displacement.
Minimum mechanism: Water must be incompressible and fill a rigid container; wooden block must be less dense than water and remain in static equilibrium; stones must be denser than water and sink without adhering to block or cup walls.
(ii)Storyline: Frame 0–2: Static shot of transparent cup with water on table. Frame 3–4: Wooden block lowered vertically into water, coming to rest floating. Frame 5–9: One stone enters frame from top, impacts water surface, sinks; water level visibly rises; block remains stable. Repeat per stone. All events occur from fixed frontal/slightly angled viewpoint ensuring full visibility of cup interior, water surface, block waterline, and stone entry points. No occlusion of key interfaces (water-air, water-block, stone-water).

Manual:
Experimental Procedure
1. Place a transparent cup filled with clear water on a flat table.
2. Gently lower a wooden block into the water so it floats freely, not touching cup walls or bottom.
3. Add small stones one by one into the water, keeping the block floating and untethered.
Observation of Experimental Phenomena
- Water level rises steadily with each stone added.
- Wooden block remains floating at constant submersion depth (same portion underwater).
Summary of Experimental Principles
- Buoyant force equals weight of displaced water; adding stones increases total weight in cup, raising water level to displace additional volume — but since wooden block floats, its submerged volume depends only on its own weight, which is unchanged.

Prompt Grounding rubric:
level_1: The transparent cup, the water inside it, the wooden block, and the small stones do not all appear together; for example the cup is opaque or metallic so its interior cannot be seen, no water is visible inside the cup, the wooden block never appears, or no small stones are ever added; or the video opens before the cup is already resting on the table.
level_2: The transparent cup (with visible water), the wooden block, and the small stones all appear on screen at some point, but the order or placement is wrong: stones are dropped into the cup before the wooden block has been placed and is floating, the block is lowered into the cup before the cup is resting on the table, or the wooden block touches the inner wall of the cup at any frame.
level_3: The transparent cup sits on the table with water clearly visible inside; the wooden block is lowered into the water and floats; small stones are then added into the cup one at a time; the block never touches the cup's inner wall; every action happens in the correct order (cup on table, then block placed and floating, then stones added) within one continuous, uncut scene.
level_4: Everything described in the 3-point level is true. In addition, the wooden block stays floating on the surface for the entire video (it never sinks or comes to rest on the cup's bottom), each stone is added individually with no two stones entering the cup at the same instant or clumped together, and the cup itself is never lifted, slid, or repositioned on the table.
level_5: Everything described in the 4-point level is true. In addition, the wooden block keeps the same upright orientation throughout (it does not spin, tip, or tumble while being placed or while stones land nearby), each stone remains clearly separate and visible as it enters the water (no two stones overlapping or hiding one another), the water surface stays calm except for the small ripples produced by each stone's splash, and no object appears or disappears partway through the sequence.

Scientific and Causal Correctness rubric:
level_1: The water level does not rise at all while stones are being added; or the wooden block fully submerges/sinks at any point; or the block's depth of submersion visibly changes as stones are added; or water overflows the cup without any prior visible rise in level.
level_2: The water level rises as stones are added, but the wooden block's submerged depth changes as a result (the block appears to ride noticeably higher or sink slightly lower in the water); or the block keeps floating but the water level stays completely flat despite stones being dropped in; or the stones themselves float or hang suspended in the water instead of sinking to the bottom.
level_3: The water level rises steadily each time a stone is added; the wooden block remains floating; the depth to which the block is submerged does not increase or decrease as stones are added; each stone sinks to the bottom of the cup promptly after entering the water.
level_4: Everything described in the 3-point level is true. In addition, the water level rises in one direction only (it never drops or recoils between stone additions), and the wooden block shows no sign of buoyancy instability such as persistent bobbing, tilting, or rocking beyond a brief, gentle settling motion right after being placed.
level_5: Everything described in the 4-point level is true. In addition, each individual stone produces its own small, discernible rise in the water's meniscus (the rise is roughly proportional to the number of stones added rather than happening in one sudden jump), and no stone ever touches or nudges the wooden block as it sinks past it.

Spatiotemporal Consistency rubric:
level_1: The wooden block or stones teleport or pop into existence (e.g., the block is shown floating with no entry motion, or a stone appears mid-air or already submerged with no visible fall); or lighting jumps abruptly between frames (e.g., a fully lit scene cuts to a fully shadowed one in a single frame); or a structural break occurs, such as the cup cracking, water leaking through its base, or the wooden block visibly disintegrating.
level_2: Noticeable but less severe discontinuities occur: the cup flickers between looking transparent and opaque; the wooden block vanishes from view for two or more consecutive frames; the water's surface freezes in place while a stone is still visibly falling toward it; or the camera angle suddenly zooms, pans, or rotates with no corresponding camera movement shown.
level_3: The cup stays fixed in the same spot on the table, the wooden block is lowered into the cup from above, and each stone drops into the cup from above, all with no teleporting, no cracking or structural breaks, no sudden lighting jumps, and no unexplained camera-angle changes; every motion looks physically plausible and unfolds continuously.
level_4: Everything described in the 3-point level is true. In addition, the wooden block descends straight down into the water with no sideways drift, each stone falls straight down without veering sideways, the ripples each stone creates spread outward in even circles from its point of entry, and no stone's splash blocks the view of the wooden block or the water surface for more than a passing instant.
level_5: Everything described in the 4-point level is true. In addition, the block's waterline (where water meets the block) stays clearly visible and does not flicker, blur, or jump from frame to frame; motion throughout the clip is smooth with no stroboscopic jumps or mismatched blur (e.g., a crisp stone falling next to a blurred water surface); and the depth relationship between the cup/water in the foreground and the table/background stays consistent and stable throughout.