Domain: Healthcare — Nutrition & Dietetics
Target concept: Sodium benzoate as a preservative

Video generation prompt: At 25°C, two transparent glasses are placed side by side on a table. The glass on the left contains an appropriate amount of freshly squeezed apple juice, while the glass on the right contains an equal volume of the same apple juice. Sufficient 0.1% sodium benzoate is added to the right glass, and the scene is continuously filmed for several days.

Evaluation guide:
(i) Target concept: Sodium benzoate acts as a microbial preservative in acidic fruit juice by suppressing spoilage organisms.
Minimum mechanism: Apple juice must be unpasteurized and susceptible to ambient microbial contamination; sodium benzoate must be present at effective concentration (≥0.05%) in acidic medium (pH < 4.5) to remain undissociated and biologically active; spoilage requires time and ambient microbes to manifest visibly as cloudiness, pellicle, or sediment.
(ii)Storyline: Frame opens on static overhead/slightly angled tabletop view showing two identical transparent glasses side-by-side. Both filled with amber apple juice at equal height. A hand enters from right, delivers sodium benzoate solution exclusively into right glass (visible droplet entry), then withdraws. Scene holds steady: no camera motion, no occlusion. Over simulated multi-day progression (accelerated via time-lapse or morph), left glass progressively develops at least one spoilage indicator (cloudiness/film/sediment), while right glass remains optically identical to baseline; no haze, no particles, no film, no color shift. Contrast must be visually unambiguous and sustained.

Manual:
Experimental Procedure
1. Place two identical transparent glasses side-by-side on a flat table.
2. Pour freshly squeezed apple juice into both glasses to identical visible levels.
3. Add 0.1% sodium benzoate solution to the right glass only, using a dropper or pipette.
Observation of Experimental Phenomena
Over several days: left glass develops cloudiness, surface film, or sediment; right glass remains clear, homogeneous, and unchanged in appearance.
Summary of Experimental Principles
Sodium benzoate inhibits microbial growth in acidic foods like apple juice (pH < 4.5), preventing spoilage by yeasts, molds, and bacteria — demonstrating its function as a preservative in nutrition and healthcare.

Prompt Grounding rubric:
level_1: Neither glass shows apple juice, or only one glass appears; the two glasses are not placed side by side; or no dropper, pipette, or pour action delivering the sodium benzoate solution is ever shown.
level_2: Both glasses are present side by side and filled with juice, but something is incomplete: the liquid levels look clearly unequal between the two; or it isn't clear which glass receives the sodium benzoate (the addition action isn't clearly aimed at the right-hand glass alone); or the addition action touches or drifts toward the left glass too.
level_3: Two identical transparent glasses sit side by side, both filled with apple juice to matching levels; a visible addition action delivers sodium benzoate solution into the right-hand glass only, while the left-hand glass receives no such addition.
level_4: In addition to everything at the 3-point level, the addition action is unmistakably confined to the right glass (the dropper or hand enters, dispenses, and withdraws without ever nearing or touching the left glass), and nothing else in the frame (extra containers, labels, a second hand) contradicts which glass was treated.
level_5: In addition to everything at the 4-point level, both glasses stay upright, fully visible, and in the same relative position for the entire multi-day span shown; the framing never shifts in a way that hides either glass; the sodium benzoate addition happens as a single, clean action into the right glass only, with no repeated dosing and no doubt about timing or target.

Scientific and Causal Correctness rubric:
level_1: No visible difference develops between the two glasses over the days shown; or both develop the same spoilage signs; or the right-hand (treated) glass is the one that spoils while the left-hand (untreated) glass stays clear, the reverse of what sodium benzoate should produce; or a change appears that has nothing to do with microbial spoilage, such as the juice turning an unrelated color like blue, solidifying, or producing bubbles with no accompanying cloudiness or film.
level_2: A visible change appears in only one glass, but it's the wrong one: only the right (preserved) glass changes; or both glasses change in the same way with no contrast between them; or the change that does appear, such as a uniform color fade or crystal formation, doesn't resemble the cloudiness, film, or sediment typical of microbial juice spoilage.
level_3: The right glass (with sodium benzoate) shows none of the following: cloudiness, a surface film, sediment, or discoloration beyond its starting shade; the left glass (plain juice) shows at least one of these: visible cloudiness, a film on the surface, settling sediment, or a color shift from its original amber.
level_4: In addition to everything at the 3-point level, the right glass stays visibly clear for the entire span shown, without any brief cloudy moment or partial film that later clears; the spoilage signs in the left glass visibly worsen over the shown days (film spreading, cloudiness thickening, sediment building up) rather than staying static or clearing up on their own.
level_5: In addition to everything at the 4-point level, by the end the left glass shows at least two distinct spoilage signs together (for example, cloudiness together with a surface film, or sediment together with a color shift), while the right glass shows none of these at any point, keeping its original clarity and color the whole time.

Spatiotemporal Consistency rubric:
level_1: A glass disappears from its spot and reappears somewhere else; the juice level changes with no addition, spill, or evaporation shown to explain it; the room's brightness suddenly swaps between very bright and very dark with no visible transition; a glass's shape warps or stretches; or something in the background pops in or out of existence.
level_2: One clear break in continuity occurs: a glass sits in a slightly different spot between shots with no visible reason; the juice's surface holds perfectly still for a stretch and then abruptly changes state with no transition shown; the shadows the glasses cast swing to the opposite side even though the light source doesn't appear to move; or a glass rim looks like it briefly cracks or softens and then is back to normal.
level_3: Both glasses stay in the same position and orientation for the whole clip; the juice's surface moves the way a real liquid would (small ripples settling out, no unexplained jumps in level or state); the light's direction and the shadows the glasses cast stay put; nothing in the background flickers or disappears.
level_4: In addition to everything at the 3-point level, any hand or dropper entering the frame moves along a smooth path, slows before touching the liquid, and withdraws without a sudden jerk; the dropper never appears to pass through the glass wall; if sediment forms in the left glass, it visibly settles over time rather than appearing instantly at the bottom.
level_5: In addition to everything at the 4-point level, the clip plays as one unbroken shot with no visible cuts; the two glasses' relative distance and size stay consistent, showing no camera drift; any motion blur present matches how fast something is actually moving rather than appearing and disappearing at random; the edges of both glasses stay clear and well-defined rather than flickering or losing focus.