Domain: Engineering — Hydraulic Engineering
Target concept: Eutrophication of water quality

Video generation prompt: Three small-scale eutrophication simulation devices (three transparent containers, each containing clear water, nutrient solution with nitrogen and phosphorus, and nutrient solution with nitrogen and phosphorus plus algae) are displayed in parallel. Procedure: place the three containers under identical lighting conditions, and continuously photograph the transparency and color changes of the water in each container over several days, to demonstrate the relationship between algal growth and eutrophication.

Evaluation guide:
(i) Target concept: Visual demonstration of eutrophication onset via algal biomass-induced color and transparency change, unfolding gradually over the depicted days rather than as an instant, fixed contrast.
Minimum mechanism: Algae require nitrogen and phosphorus to grow; as the live suspended algae population increases over the days represented in the time-lapse, it scatters more light (reducing transparency) and absorbs/reflects green wavelengths more strongly (producing a deepening green hue); growth is gradual, so the visual change should build up across the clip rather than being present at full strength from the first frame.
(ii)Storyline: Frame 1 (start of the time-lapse, representing day zero): three transparent containers sit in a fixed left-middle-right arrangement under one unmoving camera and constant lighting; all three look colorless/translucent and nearly indistinguishable. As the clip advances (compressing several elapsed days into its runtime): the left container (plain water) and the middle container (nitrogen-phosphorus solution only) stay colorless and transparent the whole time; the right container (nitrogen-phosphorus solution with algae) gradually develops a green tint and grows hazier, reaching a clearly green, turbid appearance by the final frames. No pouring, mixing, or hand intervention ever occurs; the viewer reads the algal growth from this progressive change in the right container relative to the two unchanging containers beside it.

Manual:
Experimental Procedure
Place three identical transparent containers side-by-side: left contains clear water, middle contains nitrogen-phosphorus nutrient solution, right contains the same nutrient solution inoculated with algae. Keeping the camera and lighting fixed, record a time-lapse spanning several days (compressed into a short clip) to capture how each container's transparency and color change over that time.
Observation of Experimental Phenomena
Left container: stays colorless and fully transparent for the entire time-lapse.
Middle container: stays colorless and fully transparent for the entire time-lapse.
Right container: looks similar to the other two at first, then gradually turns green and grows less transparent as the days pass, ending clearly green and turbid.
Summary of Experimental Principles
Eutrophication is nutrient-driven algal proliferation: nitrogen and phosphorus alone do not discolor water, but when algae are also present, those nutrients let the algae multiply over the following days, and it is this growing algal population that produces the green coloration and turbidity — a visual indicator of eutrophication that builds up gradually rather than appearing all at once.

Prompt Grounding rubric:
level_1: Fewer than three transparent containers appear on screen, the containers are not arranged left-to-right for comparison, or one or more of the three required contents (plain water, nitrogen-phosphorus nutrient solution, and nutrient solution with algae) is not visibly present.
level_2: Three transparent containers are shown side by side, but at least one fails to visually match its intended content in the opening frame (for example, two containers look identical when they are supposed to hold different solutions), or the containers are lit so unevenly that comparing them is unreliable (e.g., one container sits in strong shadow while its neighbors are brightly lit).
level_3: Three transparent containers sit side by side on the same surface: left holds clear water, middle holds the nitrogen-phosphorus nutrient solution, right holds the same nutrient solution with algae added; in the opening frame all three look colorless or near-colorless, and lighting is even enough that any later differences can be attributed to the containers' contents rather than to lighting.
level_4: Everything at level 3 is present, and the left-to-right order (clear water, nutrient-only, nutrient plus algae) stays legible for the whole clip (no container is relabeled, swapped, or reordered), and none of the three containers is ever poured from, stirred, or physically disturbed; any change visible in the clip comes only from the passage of the depicted days, not from an action performed on the containers.
level_5: Everything at level 4 is present, and the fixed camera framing keeps all three containers fully in view, at the same relative spacing and position, for the entire clip: no container is cropped out, occluded, or repositioned, and the viewpoint never pans, zooms, or cuts away from the three-container comparison.

Scientific and Causal Correctness rubric:
level_1: By the end of the clip, no container shows a green tint or loss of clarity anywhere; or a green tint shows up in the clear-water or nutrient-only container instead of the algae container; or all three containers turn green together; or the algae container is already green in the very first frame with no visible growth process.
level_2: The nutrient-plus-algae container does turn green, but so does at least one of the other two containers; or the green tint flickers on and then disappears rather than persisting and growing; or the container clouds up with a color or texture inconsistent with algae (for example, a white or gray sediment settling at the bottom rather than an evenly suspended green tint).
level_3: Only the nutrient-plus-algae container develops a green tint and reduced transparency; the clear-water and nutrient-only containers stay colorless and transparent for the whole clip; the green tint in the algae container builds up gradually across the clip rather than being present at full strength in the opening frame.
level_4: Everything at level 3 is present, and the green tint and cloudiness in the algae container increase steadily from the start of the clip to the end (each later frame looks at least as green and turbid as the frame before it, with no frame reverting to a clearer or less-green state), while the other two containers show no comparable drift toward green over the same period.
level_5: Everything at level 4 is present, and the greening in the algae container looks like a real suspended algal population (an even tint spread through the whole liquid rather than a glossy film, a ring at the surface, or sediment settled at the bottom), thickening gradually across the whole container rather than in isolated blotches or streaks.

Spatiotemporal Consistency rubric:
level_1: One of the three containers vanishes or appears from nowhere between frames, or jumps to a new spot on the table; a container's size or tilt changes abruptly frame to frame; the light source appears to move or switch on and off partway through the clip, changing where the shadows fall; or the background/table surface visibly warps, tears, or distorts, or a container's edges strobe/judder between frames as if misaligned.
level_2: A container drifts slightly out of its original spot relative to the other two (a small but visible sideways shift, roughly less than 10% of the container's width), the shadows cast by the containers swing to a different direction for a few frames before settling back, or the camera itself wobbles slightly rather than holding a fixed shot.
level_3: All three containers stay in the same spot relative to each other and the table edge for the whole clip; the light comes from one consistent direction throughout, so shadows keep the same length and angle; the camera does not pan, tilt, or zoom at any point.
level_4: Everything at level 3 is present, and none of the three containers rotates, tips, or changes apparent size over the course of the clip; the boundary between each container and the table, and the liquid surface inside each container, stay visually sharp rather than smearing or blurring between frames.
level_5: Everything at level 4 is present, and the three containers appear to stay in the same positions and spacing on the table from the first frame to the last, with no visible sliding, wobble, or repositioning of any container at any point in the clip, and no stray frame shows duplicated or skipped motion.