Domain: Engineering — Hydraulic Engineering
Target concept: Water quality affects steel corrosion

Video generation prompt: Three identical steel specimens are displayed side by side, each fully immersed in a clear container filled with distilled water, saline water, and acidic water, respectively. The camera continuously records the surface of all three specimens for ten seconds without cutting or panning away.

Evaluation guide:
(i) Target concept: Differential electrochemical corrosion kinetics of carbon steel across aqueous environments differing in pH and ionic strength.
Minimum mechanism: Steel must be exposed to aqueous electrolytes where H+ (acidic) and Cl- (saline) act as aggressive species that sustain rapid anodic Fe -> Fe2+ oxidation coupled with cathodic O2/H+ reduction; distilled water has low ionic conductivity and no aggressive ions, so the same oxygen-absorption corrosion proceeds far more slowly there, producing only a small, delayed rust spot within the 10-second window rather than the rapid, extensive rusting seen in the acidic and saline samples.
(ii)Storyline: Frame 0-2s: Three identical steel specimens fully immersed side-by-side in three clear containers; liquids visually distinct per type (distilled: clear/colorless; saline: clear + micro-crystals; acidic: clear + pale amber). Frame 2-4s: First orange-brown rust spot appears only on the acidic specimen surface. Frame 4-6s: Second rust spot appears only on the saline specimen; acidic rust expands visibly. Frame 6-8s: A small, faint third rust spot appears only on the distilled specimen, visibly smaller and fainter than the other two at this point; saline rust expands; acidic rust covers the largest area. Frame 8-10s: All three rust areas continue expanding, maintaining the coverage order acidic > saline > distilled; no rust detachment, bubbling, or color deviation; a fixed frontal view keeps all specimens and containers fully visible and spatially stable throughout.

Manual:
Experimental Procedure
1. Place three identical polished steel specimens into three identical clear glass containers.
2. Fill container A with distilled water, container B with saline water (NaCl solution), container C with acidic water (dilute HCl solution).
3. Position all three containers side-by-side under fixed frontal view.
4. Record continuously for 10 seconds, capturing surface changes on all specimens.
Observation of Experimental Phenomena
- Rust (orange-brown discoloration) appears first on acidic water specimen, then saline, then distilled.
- Rust coverage expands continuously on each specimen, with largest area in acidic, intermediate in saline, smallest in distilled.
- No rust appears before full immersion; no rust appears on non-immersed parts.
Summary of Experimental Principles
Water quality directly influences electrochemical corrosion rate of steel: acidic conditions accelerate anodic dissolution and cathodic hydrogen evolution; saline water provides conductive electrolyte and chloride ions that penetrate passive layers; distilled water lacks ions and thus supports minimal corrosion.

Prompt Grounding rubric:
level_1: None of the three steel specimens appear; no containers are shown; the three water types (distilled, saline, acidic) are not differentiated in any way; the specimens are stacked, hidden, or shown one at a time rather than together; no specimen is immersed in liquid.
level_2: Three containers appear but are arranged in a row that is not clearly side by side (e.g., staggered depth or diagonal placement); at least one container holds liquid, yet all three liquids look identical in transparency, color, and surface texture; the steel specimens are missing, only partly submerged, or fewer/more than three are shown.
level_3: Three identical steel specimens sit side by side, each fully submerged in one of three identical clear containers, also arranged side by side; every container holds liquid; the three liquids look the same as one another, with no visible cue distinguishing distilled, saline, or acidic water.
level_4: Everything required for score 3 is shown, and in addition: the distilled water looks clear and colorless, the saline water looks clear and colorless but shows visible salt crystals settled or floating in it, and the acidic water looks clear with a faint yellow or amber tint; none of the three liquids looks cloudy or opaque; all three containers share the same shape and size.
level_5: Everything required for score 4 is shown, and in addition: the specimens sit in identical positions within their containers (same depth, same orientation) so the three setups are directly comparable; the distilled water shows no particles at all; the saline water's crystals are visibly settled at the bottom or gently suspended; the acidic water keeps a steady pale amber tint with no brown coloring yet; no extra objects, hands, or labels appear in the frame.

Scientific and Causal Correctness rubric:
level_1: None of the three specimens shows any sign of corrosion; every specimen stays a uniform metallic gray for the whole ten seconds; no orange-brown color, texture change, or surface disruption appears anywhere.
level_2: Rust shows up on only one specimen but in the wrong color (black, blue, green, or purple instead of orange-brown); or all three specimens rust at the same time with the same speed and extent; or rust appears before any specimen is fully immersed.
level_3: All three specimens develop small, isolated orange-brown spots only after they are fully immersed; the spots grow larger over time on each specimen, but the speed and final size of the rust patches look about the same across acidic, saline, and distilled -- there is no visible ranking among the three.
level_4: Rust appears on all three specimens only after full immersion, always in orange-brown; the acidic specimen shows the first and fastest-growing rust, ending with the largest patch; the saline specimen is second, with an intermediate amount of rust; the distilled specimen is last and slowest, ending with the smallest visible rust patch; no specimen's ranking is swapped with another's.
level_5: Everything required for score 4 holds, and in addition: the acidic specimen's first rust spot appears before the saline specimen's first spot, which in turn appears before the distilled specimen's first spot; from that point on, the acidic specimen's rusted area stays visibly larger than the saline specimen's, which in turn stays larger than the distilled specimen's, all the way to the end of the clip; no rust flakes off, no bubbling occurs, and no specimen shows pitting without the accompanying orange-brown surface discoloration.

Spatiotemporal Consistency rubric:
level_1: Any of the three specimens or containers jumps to a different position or vanishes and reappears between frames; the camera's lighting flips from bright to dark with no transition; a rust patch appears or disappears instantly instead of growing; a specimen's edges distort or bend unnaturally.
level_2: A specimen or container partially disappears and comes back later in the clip; a container's outline flickers or briefly dissolves; a rust patch jumps from absent to a large area in one step with no visible growth in between; the camera pans, tilts, or rotates at any point during the ten seconds.
level_3: The camera holds one fixed frontal view for the entire clip; all three containers and specimens stay fully visible and in place the whole time; each rust patch grows gradually rather than jumping in size; no specimen bends, warps, or breaks apart; no sudden flash or blackout in lighting.
level_4: Everything required for score 3 holds, and in addition: the camera shows no jitter, no motion blur, and no flicker; all three containers and specimens keep the same size, shape, and spacing relative to each other throughout; each rust patch grows in a smooth, gradual way rather than in visible steps; nothing ever blocks the view of any specimen or container.
level_5: Everything required for score 4 holds, and in addition: none of the three containers or specimens ever drifts, shifts, or becomes misaligned relative to the others across the whole clip; each rust patch's growth never pauses, shrinks, or reverses; the lighting stays even and steady from first frame to last, with no stray reflections or lens artifacts appearing or disappearing on the glass containers.