Domain: Natural Science — Geology & Geophysics
Target concept: Calcite and Dolomite Identification Experiment (Alizarin Red Staining Method)

Video generation prompt: Take equal amounts of dolomite and calcite powder on two white glass slides, add one drop of alizarin red solution to each, and let stand for 2 seconds.

Evaluation guide:
(i) Target concept: Selective alizarin red staining distinguishes calcite from dolomite based on differential calcium ion accessibility in carbonate lattice.
Minimum mechanism: Alizarin red must be applied as discrete aqueous droplets to dry, unmixed, spatially separated mineral powders; color development requires direct molecular contact and occurs only where reactive Ca²⁺ sites are exposed and unblocked by Mg²⁺ substitution.
(ii)Storyline: [Start] Two identically sized, matte white glass slides enter static frame, positioned side-by-side. [Event 1] Dry, granular dolomite powder appears on left slide; dry, granular calcite powder appears on right slide — both powders retain discrete particle morphology and no overlap. [Event 2] Dropper approaches each slide sequentially or simultaneously; one spherical droplet detaches and lands centered on each powder pile with no splash or runoff. [Event 3] During 2-second stand time: calcite particles visibly acquire red/pink chroma while retaining shape and location; dolomite particles show zero chromatic deviation and no swelling/dissolution. [Visibility constraint] Entire sequence captured from fixed frontal viewpoint; no occlusion; consistent illumination ensures unambiguous color discrimination between samples.

Manual:
Experimental Procedure
1. Place equal amounts of dry dolomite powder on left white glass slide and dry calcite powder on right white glass slide.
2. Using a dropper, apply one drop of alizarin red solution to each powder pile.
3. Let stand undisturbed for 2 seconds.
Observation of Experimental Phenomena
Calcite powder turns red or pink; dolomite powder remains unchanged (white/off-white).
Summary of Experimental Principles
Alizarin red selectively chelates with calcium ions in calcite (CaCO₃), forming a red complex; dolomite (CaMg(CO₃)₂) lacks sufficient free Ca²⁺ sites for rapid staining under this method, so no color develops.

Prompt Grounding rubric:
level_1: No white glass slides appear; no dolomite or calcite powder is shown; no dropper or alizarin red solution appears; the two-sample side-by-side setup and the single-drop application are both absent.
level_2: One white glass slide with one powder sample (dolomite or calcite, not both) appears, or the alizarin red solution is shown but never actually dropped onto a sample; the two slides are not shown side by side in the same shot.
level_3: Two white glass slides sit side by side in the same shot, each holding a separate dry powder pile - dolomite on one slide, calcite on the other - and a single drop of alizarin red solution is applied to each pile with no smearing or reagent mix-up.
level_4: Everything required for a 3 is met, and in addition: the dolomite and calcite slides are clearly distinguishable by their left/right position; the dropper visibly approaches and releases directly above each pile so the drop lands centered on it; nothing (fingers, labels, tools) blocks the view of either pile during the drop or the 2-second stand time.
level_5: Everything required for a 4 is met, and in addition: both slides stay still and unobstructed throughout; exactly one drop lands on each pile with no splatter or secondary droplets; both powder piles keep their original shape and position before and after the drop lands; and no motion blur or skipped frame hides the moment either drop makes contact or the start of the 2-second stand time.

Scientific and Causal Correctness rubric:
level_1: Neither slide changes color, or both slides change color the same way (both turn red or both stay white), or a color change happens on the wrong slide or in the wrong hue (e.g., blue or yellow instead of red/pink), or a red/pink tint is already visible before the drop actually touches the powder (e.g., appearing while the drop is still falling or before it lands) - the calcite-versus-dolomite distinction is not shown at all, or its timing violates basic cause-and-effect.
level_2: A color change happens, but it is scientifically backwards or uninformative - e.g., the dolomite pile turns red/pink while calcite stays white, or both piles turn the same color, or the red color spreads well beyond the powder grains onto the bare slide instead of staying on the mineral.
level_3: Only the calcite pile turns red or pink while the dolomite pile stays white or off-white, and the color stays confined to the calcite grains rather than the slide around them, appearing only after the drop has actually landed on the pile - but the timing or extent of the color change is otherwise imperfect for the 2-second exposure (e.g., only a tiny corner of the calcite pile changes, or the color is slow to become visible within the 2-second window).
level_4: The calcite pile's red/pink color is confined to the solid grains with no halo bleeding onto the bare slide; the dolomite pile shows no pink or red tint anywhere, at any point during the 2-second stand time; neither pile dissolves, bubbles, or gets visibly wetted beyond the footprint of its single drop.
level_5: Everything required for a 4 is met, and in addition: the calcite's red color develops promptly after the drop lands and looks stable by the end of the 2-second stand time; the dolomite pile shows no fleeting tint at any moment, even right where the drop first lands; and the color contrast between the two piles is immediately obvious once the reaction has played out.

Spatiotemporal Consistency rubric:
level_1: The slides jump to a different position or appearance between shots; a powder pile vanishes and reappears; the dropper itself jumps to a new position with no visible motion path; the drop appears already formed in mid-air with no visible fall from the dropper; the lighting changes abruptly between the two slides; or the camera cuts between shots in a way that breaks the sequence's continuity.
level_2: One slide tilts or rotates in a way that doesn't match the frames before it; a powder pile's shape changes unnaturally between frames; the falling drop freezes or appears to move backward mid-fall; a shadow cast by a slide or the dropper suddenly points a different direction with no cause; or background elements behind the slides flicker or warp during the stand time.
level_3: Both slides stay in the same position and orientation, the powder piles keep their shape and location, the dropper's approach and release look like one continuous motion, and each drop falls smoothly straight down onto its pile; overall lighting stays even between the two slides - but the drop's fall or the 2-second stand time may feel slightly rushed or compressed compared to a natural pace.
level_4: Everything required for a 3 is met, and in addition: neither slide shows any visible shake or vibration; there is no sideways drift of the camera between the two samples; the drop's fall and the full 2-second stand time both play out at a natural, uncompressed pace rather than being visibly sped up or skipped over; and neither sample is ever blocked from view during the sequence.
level_5: Everything required for a 4 is met, and in addition: the dropper's downward motion looks physically natural (a smooth release rather than an instant snap), the drop keeps a round shape until it touches the powder, no powder grains or slide edges warp or stretch, and there is no flash, glow, or ghosting artifact that affects one sample differently than the other.