Domain: Healthcare — Nutrition & Dietetics
Target concept: Impact of Juicing on the Nutrition (Vitamin C) of Fruits and Vegetables

Video generation prompt: Use fresh fruits, knives, juicers, beakers, vitamin C indicator solution, and pipettes. Cut the fruit into pieces; juice one portion of the fruit into a beaker to obtain the fresh juice, and separately crush another portion of the fruit by hand into a pulp to obtain the crushed fruit extract; add equal volumes of the indicator to the fresh juice and the crushed fruit extract, and compare the indicator's reaction under the same conditions.

Evaluation guide:
(i) Target concept: Vitamin C degradation due to mechanical damage (crushing) accelerates oxidation, reducing its ability to reduce DCPIP indicator. Minimum mechanism: DCPIP must be blue in its oxidized state and fades toward colorless as ascorbic acid reduces it; hand-crushing must expose the fruit's vitamin C to more oxidation than juicing does, so the crushed sample fades noticeably less than the juiced sample.
(ii)Storyline: [0–2s] Fresh fruit placed beside knife → knife cuts fruit → pieces enter juicer. [2–4s] Juicer operates → juice flows continuously into first beaker. [4–6s] A separate portion of the fruit is crushed by hand into pulp and placed into the second beaker. [6–8s] Pipette draws indicator, then dispenses one droplet into each beaker synchronously while both beakers remain adjacent and fully in-frame. [8–10s] Both beakers held static in side-by-side composition; a clear color difference stabilizes and remains visually unambiguous: the fresh-juice beaker noticeably paler than before, the crushed-extract beaker visibly bluer by comparison; no further fading, mixing, or drift once the difference is established.

Manual:
Experimental Procedure
1. Cut fresh fruit with knife into pieces.
2. Juice one portion of the fruit using the juicer into a beaker to obtain the fresh juice.
3. Separately crush another portion of the fruit by hand into a pulp to prepare the crushed fruit extract in a second beaker.
4. Use pipette to add equal volumes of blue vitamin C indicator solution to both beakers.
5. Observe and compare the color change side-by-side.
Observation of Experimental Phenomena
Fresh juice + indicator: the blue color fades substantially, becoming noticeably paler. Crushed fruit extract + indicator: the blue color fades much less, remaining visibly darker/stronger than the fresh-juice sample by comparison.
Summary of Experimental Principles
Vitamin C (ascorbic acid) reduces the blue DCPIP indicator toward a colorless form, and the more active vitamin C is available, the more the blue color fades. Juicing exposes the fruit to comparatively little air, so the fresh juice still holds enough active vitamin C to fade the indicator substantially. Hand-crushing exposes the fruit's cells more thoroughly to oxygen and to the fruit's own oxidative enzymes (such as ascorbate oxidase), degrading more of its vitamin C before testing — so the crushed extract reduces the indicator less and stays comparatively bluer.

Prompt Grounding rubric:
level_1: None of the required items (fresh fruit, a knife, a juicer, beakers, the vitamin C indicator solution, or a pipette) appear in the scene, or the scene shows an entirely different setup with no fruit-testing activity at all.
level_2: At least one required item appears (for example, fruit or a beaker) but fewer than three of the six required items (fresh fruit, knife, juicer, beakers, indicator solution, pipette) are shown; there is no visible juicing or crushing of the fruit, and no indicator being added to anything.
level_3: All six required items appear at some point (fresh fruit, a knife, a juicer, two beakers, the blue indicator solution, and a pipette); juice is extracted from the fruit into one beaker, and the indicator is added to at least one sample; however, the two samples (the fresh juice and the separately crushed fruit extract) are never shown together side by side, or it is unclear that they are two distinct preparations rather than the same liquid twice.
level_4: All six required items remain visible through the relevant steps: the fruit is cut and juiced into one beaker, a separate portion of the fruit is crushed by hand into a pulp for the second beaker, and the pipette adds the indicator to both beakers; the two beakers are shown together in the same frame, close enough to compare directly; no beaker or ingredient disappears or is blocked from view during these steps.
level_5: All six required items are shown, clearly identifiable, and remain in frame without unexplained repositioning: the fruit is cut with the knife, juiced into the first beaker, and a separate portion is crushed by hand into the pulpy second sample in the second beaker; the pipette adds equal, visibly matched volumes of indicator to both beakers in view of the camera; the two beakers stay side by side, unobstructed, and unmoved for the remainder of the video so their colors can be compared directly.

Scientific and Causal Correctness rubric:
level_1: Neither beaker shows any color change from the indicator's initial blue, or the color change shown is not related to vitamin C chemistry at all (e.g., the indicator turns a color other than fading toward pale or colorless, such as red or green).
level_2: Only one of the two beakers shows any fading of the blue color while the other stays fully blue and unchanged, so there is no basis for comparing the two samples; or both beakers fade by the same amount, showing no difference between the fresh juice and the crushed extract.
level_3: Both beakers show some fading of the blue indicator color, and the fresh-juice beaker fades noticeably more than the crushed-extract beaker (a difference exists in the expected direction), but the difference is small, inconsistent, or hard to judge (e.g., partly obscured, or the two beakers look similar enough that a viewer would need to look closely to tell them apart).
level_4: Both beakers show a clear, easy-to-see difference in the same direction: the fresh-juice beaker's blue color fades substantially more than the crushed-extract beaker's, which stays noticeably more blue by comparison; the difference is stable once it appears and does not fade back or reverse during the remaining video.
level_5: The fresh-juice beaker's blue color fades the most and stays the palest of the two for the rest of the video, while the crushed-extract beaker's blue color remains visibly darker or stronger by comparison for the same duration; the contrast between the two beakers is unambiguous, consistent, and does not fluctuate, drift, or reverse at any point after it is established.

Spatiotemporal Consistency rubric:
level_1: A beaker, the knife, or the fruit appears or disappears with no visible motion causing it (e.g., a beaker is simply present in a later shot with no camera cut or hand placing it there), the juice or indicator seems to jump directly into a beaker without visibly traveling from its source, an object's shape distorts unnaturally (e.g., a beaker warps or the knife bends), or the lighting on the scene abruptly shifts between bright and dark (or vice versa) between frames with no visible cause such as a hand or shadow passing through.
level_2: Two or more of the following occur: a beaker's position or angle changes abruptly between shots without a visible motion causing it, the extracted juice does not show a continuous flow path from the juicer's spout down into the beaker, the pipette releases the indicator without any visible droplet or downward motion, or the fruit pieces move into the juicer without the knife or a hand appearing to place them.
level_3: The knife, juicer, beakers, and pipette all move and stay in stable, physically sensible positions; the juice flows in a visible, continuous stream from the juicer into its beaker; the pipette's tip touches the liquid surface before releasing the indicator; and the two beakers do not shift position on their own, but one motion in the sequence looks slightly off, such as the pipette hovering above the beaker rather than dipping to it, or the crushed pulp appearing in its beaker in a single unnatural instant rather than being placed with a visible hand or spoon motion.
level_4: Every object (the fruit, knife, juicer, both beakers, indicator bottle, and pipette) keeps a consistent size and shape as the camera holds its view; the juice's flow from the juicer into its beaker follows a natural, gravity-drawn path; the pipette releases one clean droplet into each beaker without splattering; and both beakers stay still, upright, and level once placed; the only remaining imperfection is a brief, minor flicker in a reflection off a beaker or the blade that does not recur.
level_5: Throughout the whole video, every object's motion (the knife's cut, the fruit entering the juicer, the juice's flow, the crushed pulp being prepared, and the pipette's dip-and-release into each beaker) reads as one continuous, physically coherent action with no skipped or repeated moments; both beakers stay exactly where they were placed for direct comparison; and the room's lighting on the fruit, beakers, and liquids stays even and steady, with no sudden brightening, darkening, or color-cast shift at any point.