Domain: Natural Science — Chemistry
Target concept: Sodium peroxide reaction with water

Video generation prompt: A test tube contains a small amount of yellowish sodium peroxide powder. Distilled water is added, a glowing splint is inserted, and phenolphthalein solution is dropped in.

Evaluation guide:
(i) Target concept: Exothermic redox reaction producing oxygen and alkali; minimum mechanism: Na₂O₂ must contact H₂O to generate O₂ gas (causing splint reignition) and OH⁻ ions (causing phenolphthalein color change). Powder must be solid and yellowish pre-reaction; gas must evolve visibly; splint must reignite *due to gas*, not ambient air; pink must appear *only after* phenolphthalein contacts alkaline solution.
(ii) Storyline: Frame opens on static shot of upright test tube containing granular yellowish powder. Water stream enters tube → immediate onset of upward-rising bubbles → glowing splint inserted → flame reignites *while bubbles rise* → phenolphthalein droplets descend → contact liquid surface → pink color emerges locally and diffuses radially. Fixed frontal viewpoint throughout; no camera movement; all objects remain fully in frame; lighting consistent; no off-screen actions implied.

Manual:
Experimental Procedure
1. Place small amount of yellowish sodium peroxide powder into clean dry test tube.
2. Add distilled water slowly until powder is covered.
3. Immediately insert glowing splint into test tube opening.
4. After splint reignites, add 1–2 drops of phenolphthalein solution.
Observation of Experimental Phenomena
- Vigorous bubbling/gas evolution upon water addition.
- Glowing splint reignites with sustained flame inside tube.
- Colorless solution turns pink/red after phenolphthalein addition.
Summary of Experimental Principles
Sodium peroxide (Na₂O₂) reacts exothermically with water: 2Na₂O₂ + 2H₂O → 4NaOH + O₂↑. Oxygen gas supports combustion (reignites splint). NaOH makes solution strongly alkaline, turning phenolphthalein pink.

Prompt Grounding rubric:
level_1: None of the five required setup elements from the prompt are shown: no test tube with yellowish Na2O2 powder, no distilled water addition, no glowing splint insertion, and no phenolphthalein drops entering the liquid. The video does not establish the sodium peroxide/water setup at all.
level_2: Only one or two of the five elements appear (test tube with yellow powder; water addition; glowing splint in the tube; phenolphthalein drop reaching the liquid), or three or more elements are present but clearly mislocated (e.g., the splint held outside the tube mouth, or the phenolphthalein dropper aimed at the bench rather than the tube). At least three of the five core objects/actions are missing or mislocated.
level_3: All five elements are present and roughly correctly placed: test tube with yellowish solid, water visibly added into the tube, glowing splint entering the tube opening, and phenolphthalein reaching the liquid, occurring in that general order, but one element shows minor spatial ambiguity, such as the splint's depth inside the tube being unclear or the drop's contact with the liquid surface not being clearly shown.
level_4: All of 3, plus the five elements are correctly ordered (powder, then water, then splint, then phenolphthalein) and clearly resolved: the powder sits at the tube bottom before water arrives, water visibly contacts the powder, the glowing splint's tip sits inside the tube's air space or at the liquid surface, and phenolphthalein visibly reaches the liquid, with at most one small flaw such as the splint held at a slight angle or partly hidden by the tube rim that doesn't break the visual chain of events, and no unrelated lab equipment fills more than roughly a third of the frame.
level_5: All of 4, plus the test tube is upright and fully in frame; the yellowish Na2O2 powder is clearly a solid at the tube bottom before water arrives; water is added as a visible stream that reaches the powder; the glowing splint is inserted with its glowing tip inside the tube, above the liquid; and phenolphthalein is delivered as one or two distinct drops (matching the manual's '1–2 drops' instruction) that visibly contact the liquid surface and begin to spread. No occlusion, no ambiguous object identity, and no steps shown out of order.

Scientific and Causal Correctness rubric:
level_1: None of the three expected chemical phenomena occur: the powder stays yellow with no gas evolution, the glowing splint does not reignite, and the liquid stays colorless after phenolphthalein is added. Nothing in the clip indicates a reaction between Na2O2 and water.
level_2: At most one of the three phenomena is scientifically correct (for example the splint reignites but no bubbling was ever shown, or the liquid turns pink but the powder never appeared to contact reacting water, or vigorous bubbling occurs but the splint fails to reignite and phenolphthalein causes no color change), while the other phenomena contradict the Na2O2 + H2O → NaOH + O2 mechanism, such as pink appearing before phenolphthalein is added.
level_3: Two or three of the following occur in roughly the right order: bubbling begins after water contacts the powder, the glowing splint reignites while inside the tube during or after the bubbling, and the liquid turns pink/red once phenolphthalein is added, but one phenomenon is missing, mistimed (e.g., the splint reignites before any bubbling appears), or physically odd (e.g., the pink appears as an instant flash rather than spreading).
level_4: All of 3, plus all three phenomena occur with correct causality and reasonable timing: bubbling begins within about 2 seconds of water reaching the powder and continues through the splint test, the glowing splint reignites into a flame while inserted during active gas evolution, and the liquid turns pink/red only after phenolphthalein contacts it and spreads gradually rather than flashing uniformly, with at most one small deviation, such as bubbles not clearly rising or a faint but still identifiable pink.
level_5: All of 4, plus the phenomena show full fidelity to the reaction: gas bubbles rise continuously through the liquid from the moment water touches the powder and persist through the splint test; the glowing splint reignites into a sustained flame only while inside the tube during active gas evolution and dies out if withdrawn; phenolphthalein contact produces a pink color that spreads outward from the drop site and deepens over a few seconds rather than flashing uniformly; and no contradictory cues appear, such as leftover undissolved yellow powder or a cooling mist that would misrepresent this exothermic reaction.

Spatiotemporal Consistency rubric:
level_1: Severe spatiotemporal rupture: the amount or location of powder in the tube differs between one shot and the next with no pour or hand motion to explain it, the glowing splint is already inside the tube with no insertion shown, the liquid height changes abruptly between frames without any pour or bubbling to account for it, the pink color switches fully on or off between frames instead of spreading gradually, the lighting suddenly shifts between frames with no cause, or the camera cuts or pans mid-action breaking the otherwise fixed viewpoint.
level_2: Several noticeable breaks appear: the splint appears inside the tube without a visible insertion motion, a phenolphthalein drop appears already merged into the liquid without a visible fall, bubbles sit still or drift downward instead of rising, or the pink patch spreads sideways before it spreads outward from the drop point. At least three such inconsistencies occur.
level_3: The sequence is mostly continuous, with at most one or two brief inconsistencies, such as a momentary skip during splint insertion or a slight mismatch in liquid height just before and after water is added, while the tube, splint, and dropper keep plausible, traceable positions and none of the objects change shape or split apart.
level_4: All of 3, plus all motions are physically plausible and continuous: water enters the tube in a steady visible stream and settles onto the powder, the splint moves into the tube at a steady speed along one path, phenolphthalein drops fall and visibly touch the liquid surface, bubbles rise continuously without pausing or reversing, and the pink color spreads outward from each drop's landing point with growing intensity, with at most one negligible artifact, such as a brief blur on a falling drop, that doesn't change how the event reads.
level_5: All of 4, plus the whole sequence reads as one continuous, physically consistent event from powder to pink diffusion: no object skips position, floats, or changes shape at any point; the liquid surface only moves in ways caused by the water pour, the splint's entry, or rising bubbles; the bubbles keep rising and getting smaller as they near the surface; and the pink coloration keeps expanding outward from each drop's landing point in a smooth, non-flickering way from the moment phenolphthalein lands until the end of the clip.