Domain: Natural Science — Chemistry
Target concept: Borax Detection (Curcumin Colorimetric Method)

Video generation prompt: Use a pipette to add a few drops of curcumin reagent to a test tube containing an appropriate amount of borax, stir gently with a glass rod, and then briefly heat the mixture using a low flame or a hot plate.

Evaluation guide:
(i) Target concept: Colorimetric detection of borate ions via curcumin complexation, requiring hydrolysis, ligand binding, and thermal stabilization.
Minimum mechanism: Borax must first dissolve/hydrolyze to release boric acid; curcumin must be in acidic or neutral aqueous medium to undergo condensation; heating drives dehydration to form stable red-brown rosocyanine-type chromophore.
(ii)Storyline: Frame 1–2: Static shot showing test tube with white borax crystals. Frame 3–4: Pipette enters frame, draws curcumin from bottle, descends vertically into test tube opening, and dispenses discrete droplets → mixture turns yellow-orange. Frame 5–6: Glass rod enters, immerses fully, rotates gently → no color change. Frame 7–8: Heat source activates beneath test tube base → mixture begins uniform red-brown transition. Frame 9–10: Final stable red-brown color fully developed; all tools remain in consistent spatial relationship; fixed frontal mid-shot maintains full visibility of test tube, reagent delivery, stirring, and heating zone.

Manual:
Experimental Procedure
1. Place a small amount of white borax powder in a clean test tube.
2. Using a pipette, add 2–4 drops of amber-yellow curcumin reagent into the test tube.
3. Insert a glass rod and stir gently to mix.
4. Heat the bottom of the test tube steadily with a low flame or hot plate for ~5 seconds.
Observation of Experimental Phenomena
The mixture changes from colorless/white → yellow-orange after curcumin addition, then uniformly transitions to red-brown only after heating begins.
Summary of Experimental Principles
Borax (Na₂B₄O₇·10H₂O) hydrolyzes in water to release boric acid, which reacts with curcumin to form a red-brown complex; heating accelerates the reaction and stabilizes the colored product.

Prompt Grounding rubric:
level_1: No test tube, curcumin reagent bottle, pipette, glass stirring rod, or heat source (flame or hot plate) appears in frame around the borax sample; or every object is present but none of the actions (adding curcumin, stirring, or heating) is actually performed.
level_2: At least one of the five core items (test tube, curcumin bottle, pipette, glass rod, heat source) is missing or replaced with something implausible; the pipette never visibly releases liquid into the tube, the glass rod never touches the mixture, and no heat source is ever applied to the tube; or the depicted order contradicts add, then stir, then heat.
level_3: A test tube holding a white, powdery solid (borax) is shown; the pipette dispenses liquid into the tube; the glass rod contacts the mixture inside the tube; a heat source (flame or hot-plate surface) appears in frame; all four objects and the three actions are present, but their spatial relationship is imprecise: the pipette tip doesn't clearly enter the tube's opening, the rod isn't clearly immersed in the liquid, or the flame isn't positioned under the tube's base.
level_4: The test tube, curcumin bottle with its pipette, glass rod, and heat source are all correctly identified and positioned: the pipette tip visibly enters the tube's opening and releases drops, the glass rod sits immersed and turns gently inside the tube, and the heat source sits directly beneath the tube's base; the add, stir, heat order and every spatial relationship are correct, with nothing extraneous interrupting the demonstration.
level_5: All of the 4-score criteria are met, and additionally: the pipette releases 2-4 visibly separate, non-merged drops into the tube; the glass rod's stirring motion stays continuous and gentle with no lifting out mid-stir; the heat source stays active under the tube for the whole heating phase; nothing unexpected enters or leaves the frame; the camera holds one fixed view of the tube and tools throughout, without cutting or zooming.

Scientific and Causal Correctness rubric:
level_1: The mixture never changes color at any stage (it stays white/cloudy from borax throughout), or it turns a hue unrelated to the curcumin reaction (e.g. blue, green, or black) with no visible connection to either the reagent addition or the heating step.
level_2: Only one of the two expected color changes is shown (for example the mixture jumps straight from white to red-brown without ever passing through a yellow-orange stage right after the curcumin is added, or it turns yellow-orange on addition but never reaches red-brown once heating starts), or a color shift happens at the wrong moment, such as red-brown appearing before the heat source is switched on.
level_3: Both expected transitions appear in the right order: the white, cloudy borax mixture turns yellow-orange as soon as the curcumin reagent is added (before any heating), and it then progresses to red-brown once the heat source is switched on, with no bubbling, smoking, or precipitate forming at any point, but the shifts look patchy or abrupt, or a little unmixed color lingers in the tube.
level_4: All of the 3-score criteria are met, and additionally: the yellow-orange stage stays stable and unchanging while only stirring is happening (it doesn't start reddening before the heat source is on), and the red-brown that eventually forms is even across the whole mixture, with no charring, darkening past red-brown, or solid residue left behind.
level_5: All of the 4-score criteria are met, and additionally: the borax appears as fine white crystals before anything is added; the curcumin reagent looks amber-yellow just before use; the mixture becomes a uniform yellow-orange immediately after curcumin is added; and heating drives a continuous, even shift to a deep red-brown with no intermediate blue or green tint, no fading, and no separation into layers.

Spatiotemporal Consistency rubric:
level_1: The test tube, pipette, or heat source vanishes and reappears in a different spot between frames; the flame switches on or off with no visible ignition or extinguishing motion; the glass rod passes straight through the tube's wall instead of entering through its opening; the frame goes from lit to black, or the reverse, within a single cut.
level_2: The pipette's position jumps between frames instead of moving toward the tube's opening in one continuous motion; the glass rod's turning starts and stops abruptly with no smooth wind-up; the flame switches on or off with no visible transition; the liquid inside the tube shifts level or position with no stirring or heating action to explain it.
level_3: All objects maintain one continuous spatial arrangement across the sequence (the pipette stays aligned with the tube's opening, the rod stays inside the tube while stirring, the heat source stays fixed under the tube's base), and motion runs continuously with no jumps, freezes, or on/off flickering, but a minor cosmetic artifact remains, such as slight motion blur on the rod or a brief soft-focus moment, that doesn't affect the plausibility of the sequence.
level_4: Everything in the 3-score criteria holds more tightly: the test tube shows no visible size or perspective drift; the rod dips into and stays within the liquid without ever crossing through the glass wall; the pace of pipetting, stirring, and heating matches how a person would actually handle these tools, with no sudden speed changes.
level_5: All of the 4-score criteria are met, and additionally: the pipette descends in a straight line down into the tube's opening rather than at an odd angle; the rod turns about its own long axis rather than wobbling end over end; the flame stays anchored under the tube's base for as long as it's lit; and no motion blur or ghosting ever makes the tube, pipette, or rod momentarily hard to make out.