Domain: Natural Science — Environmental Science
Target concept: Dioxin Detection (Immunochromatographic Test Paper Simulation)

Video generation prompt: Immerse the sample end of the immunoassay strip in the water sample for 5 seconds, then remove and let it stand for 2 minutes.

Evaluation guide:
(i) Target concept: Lateral flow immunoassay procedural fidelity for environmental dioxin screening.
Minimum mechanism: Capillary action drives liquid-phase migration along nitrocellulose membrane; antibody-antigen binding is time- and orientation-dependent; control line must form independent of analyte; test line formation, if it occurs, requires specific incubation time and absence of physical disturbance.
(ii)Storyline: [Frame 0–3] Hand positions strip above water container → [Frame 4–6] Tip descends vertically, breaches water surface, submerges fully → [Frame 7–8] Tip held stationary underwater → [Frame 9–10] Strip ascends vertically, clears surface → [Frame 11–15] Strip held motionless in air, upright, tip-down → [Frame 16+] Standing phase continues; a C line emerges discretely at the control zone; a T line may or may not also emerge at the test zone depending on the water sample's actual (unspecified) dioxin content; the procedure itself does not dictate this outcome. Perspective: Fixed frontal close-up (strip + top 2 cm of container visible); occlusion-free view of strip tip, water meniscus, and C/T zones; no camera movement or zoom.

Manual:
Experimental Procedure
1. Hold immunoassay strip by upper end.
2. Immerse tip (sample end) vertically into water sample until fully submerged.
3. Hold for immersion duration implied by steady motion.
4. Remove strip fully and hold vertically in air.
5. Let stand undisturbed for duration implied by motion cessation and stability.
Observation of Experimental Phenomena
After standing, a clear red/pink (or purple, for a dye-based conjugate) control line (C) forms at the control zone, confirming that the assay ran correctly. A test line (T) may or may not also form at the test zone: its presence depends on whether the water sample actually contains dioxin, which this procedure does not specify. If a T line does form, it must appear no earlier than the C line and only after the full 2-minute standing time has elapsed, since it results from slower antibody-antigen capture kinetics compared with the excess-conjugate capture that produces C.
Summary of Experimental Principles
Dioxin detection uses lateral flow immunoassay: anti-dioxin antibodies conjugated to colloidal gold bind dioxin in the sample; the resulting complex migrates along the membrane and is captured at the test zone if dioxin is present, forming line T. The control zone captures excess, unbound conjugate regardless of dioxin presence, forming line C — so C confirms the strip functioned correctly, while T (if present) indicates a positive dioxin result.

Prompt Grounding rubric:
level_1: No immunoassay strip present; no water sample container visible; no hand or tool performing immersion; none of the three core objects (strip, water sample, hand) appear.
level_2: At least one core object appears (e.g., strip or container), but no immersion action occurs; or immersion is shown without the strip being oriented correctly (e.g., tip not downward); or no removal and standing phase is depicted at all.
level_3: Immunoassay strip is visibly immersed into a water sample container for a duration implied by motion continuity (no abrupt cut), then fully removed; strip remains stationary in air for a sustained period with no further manipulation; all three core objects (strip, water container, hand/tool) are present and functionally identifiable.
level_4: Everything described at the 3-point level is present, AND the strip is held vertically or near-vertically after removal (tip-down orientation preserved), AND the water container stays in the same fixed spot within the frame throughout both the immersion and standing phases.
level_5: Everything described at the 4-point level is present, AND the strip tip is clearly submerged below the water surface during immersion (the water meniscus visibly touching the tip), AND the strip stays completely motionless (no shaking, tilting, or repositioning) for the entire standing phase, AND the hand/tool is fully withdrawn before standing begins.

Scientific and Causal Correctness rubric:
level_1: No colored band forms on the strip anywhere; or the control line (C) and test line (T) look identical in color/intensity regardless of whether dioxin could be present, so the strip conveys no distinguishable readout; or the membrane stays a uniform, unbroken color/texture with no line ever forming.
level_2: A single band forms, but it sits at the wrong position (e.g., closer to the test zone than the control zone, or vice versa from where the strip's printed zones would be); or a band starts forming while the tip is still submerged in the water sample, before the strip has even been removed to stand; or a band forms so early during the standing phase that it could not represent completed capillary migration and antibody binding, faster than the assay's real timescale allows.
level_3: After the strip is removed and stands for the full duration, a control line (C) forms as a solid, sharp, non-blurred colored band near the strip's upper (control) zone, matching a lateral-flow assay color (red/pink for colloidal gold, or purple for a dye conjugate); a second band at the test zone (T) may or may not also be present, since the video does not specify whether the water sample contains dioxin; whichever bands appear are aligned parallel to the strip's edge and no third, extraneous band appears anywhere on the membrane.
level_4: Everything described at the 3-point level is present, AND the C line is visibly the first band to appear, forming before any T line would appear, AND if a T line is shown at all, it only becomes visible after the full 2-minute standing time has elapsed (never during the 5-second immersion or the early part of standing), AND every band shown keeps a steady width and sharp edge rather than spreading, bleeding, or fading over time.
level_5: Everything described at the 4-point level is present, AND the C line is fully formed, solid, and unambiguous by the end of the video regardless of whether a T line is also present, so the video correctly conveys that C alone certifies assay validity while T (if present) indicates the dioxin result, AND no band other than C (and, if shown, T) ever appears on the strip, AND every visible band's color and sharpness stays consistent with authentic colloidal-gold or dye-based lateral-flow chemistry (no mismatched hues, no soft or feathered edges suggesting incorrect conjugate migration).

Spatiotemporal Consistency rubric:
level_1: The strip suddenly appears in a different position between consecutive frames (teleportation) rather than moving continuously downward or upward; the water surface disappears or jumps in level without the strip's motion explaining it; the hand vanishes or appears abruptly mid-immersion; the strip visibly bends, kinks, or breaks apart while being lowered or raised; the water container itself disappears or relocates between frames; or the lighting or shadow direction flips abruptly between frames (e.g., a shadow vanishes and reappears with no cause).
level_2: The hand briefly disappears for a couple of frames while moving the strip between the immersion and removal steps, then reappears in a different grip position; the water meniscus around the submerged tip flickers on and off inconsistently rather than tracking the strip continuously; the strip rotates or twists by a large, visually obvious angle (roughly a quarter turn or more) with no corresponding hand motion to cause it; or the background/table behind the container shifts sideways when the video transitions from the immersion phase to the standing phase.
level_3: The strip's tip enters and later exits the water at the same visible surface level, and the hand's grip on the strip traces one continuous, unbroken path through the immersion, hold, and removal steps; the strip and container never flicker, warp, or change shape improperly; and the strip's cast shadow on the table or container moves gradually and continuously as the strip itself moves, rather than flipping to the opposite side or vanishing and snapping back.
level_4: Everything described at the 3-point level is present, AND the strip travels down into the water and back up along a single, visibly straight vertical path with no sideways drift or spinning, AND the water surface stays flat with no ripples spreading outward before, during, or after the immersion, AND the container sits in exactly the same spot on the table for the entire clip without sliding or tipping.
level_5: Everything described at the 4-point level is present, AND the strip's descent speed while entering the water and its ascent speed while being withdrawn each look steady and even rather than jerky or varying, AND the strip and container edges line up smoothly from one frame to the next with no visible snapping, sliding, or warping of their outlines at any point in the video.