Domain: Natural Science — Chemistry
Target concept: The oxidation of alkenes with potassium permanganate causes the purple solution to turn brown (Baeyer).

Video generation prompt: In the laboratory, a few drops of liquid alkene were added to a transparent glass beaker containing an aqueous solution of potassium permanganate, and the mixture was gently shaken.

Evaluation guide:
(i) Target concept: Baeyer oxidation of alkenes yielding MnO2 colloidal suspension.
Minimum mechanism: Alkene must be unsaturated hydrocarbon (liquid at RT), KMnO4 must be aqueous and concentrated enough to yield visible MnO2, reaction requires mild agitation to initiate and disperse product.
(ii)Storyline: [Frame 0–2] Static shot: upright transparent glass beaker filled with homogeneous purple aqueous solution. [Frame 3–4] Dropper enters frame from top; 2–3 distinct liquid droplets detach and fall vertically into solution. [Frame 5–6] Droplets contact surface → brief meniscus depression → entry into bulk. [Frame 7–9] Beaker begins gentle side-to-side oscillation → solution sloshes uniformly → purple color visibly mottles → transitions to fully brown cloudiness. [Frame 10] Final still: homogeneous brown suspension filling beaker, no purple remnants, no settling. Perspective: fixed frontal medium-close-up, beaker centered, no occlusion, consistent lighting.

Manual:
Experimental Procedure
1. Place transparent glass beaker containing aqueous potassium permanganate (purple solution) on lab bench.
2. Add 2–3 drops of liquid alkene using a dropper directly into the solution.
3. Gently shake the beaker for 2–3 seconds.
Observation of Experimental Phenomena
The purple solution turns uniformly brown during/after shaking; no other colors appear; brown appearance persists and is cloudy/homogeneous.
Summary of Experimental Principles
Oxidation of alkenes by potassium permanganate (Baeyer test) reduces Mn(VII) to Mn(IV), forming insoluble brown manganese dioxide precipitate dispersed in solution.

Prompt Grounding rubric:
level_1: No liquid alkene droplets visible; no transparent glass beaker present; no aqueous potassium permanganate solution visible; no shaking motion shown; none of the required objects or actions appear.
level_2: At least one required object appears (e.g., beaker OR purple solution OR dropper), but alkene droplets are absent, beaker is opaque or non-glass, solution is not aqueous-looking, and no shaking action occurs; sequence is unrecognizable.
level_3: Transparent glass beaker containing a purple aqueous solution is present; liquid alkene is introduced via dropper or similar tool (visible droplet(s) entering solution); gentle shaking motion is shown; all three core actions (addition, containment, agitation) occur in correct order.
level_4: All elements from 3-score are present and correctly configured: beaker is upright and stationary before/during/after addition; droplets are visibly *liquid* (not solid/gel/powder) and enter the solution (not surface-only or bouncing); shaking is continuous and involves visible fluid motion; no extraneous objects (e.g., gloves, labels, unrelated chemicals) occlude the core setup.
level_5: All elements from 4-score are present with zero deviations: beaker is identifiably transparent glass (no plastic distortion, no frosted/matte finish); solution fills beaker to consistent level pre/post-addition; droplets are *multiple* and *distinctly separate* upon entry (not merged into single blob before contact); shaking motion begins *only after* droplet contact and continues for ≥2 full visible oscillations without pause or reversal; viewpoint remains fixed and centered on beaker throughout.

Scientific and Causal Correctness rubric:
level_1: No color change observed; solution remains purple throughout; no brown precipitate or suspension appears; no visual indication of reaction; alkene addition has no discernible effect.
level_2: Color change occurs but is incorrect (e.g., purple → blue, green, or black); brown material appears but is floating as discrete flakes rather than suspended fine particles; color shift happens *before* droplet contact or during shaking only without post-shake persistence.
level_3: Purple solution visibly changes to brown *after* droplet contact and during/after shaking; brown appearance is uniform and cloud-like (not patchy or layered); change persists through end of video; no other colors (e.g., yellow, orange, gray) dominate the brown state.
level_4: All elements from 3-score are satisfied, and the brown state is *visually homogeneous* across the entire solution volume (no clear upper layer, no unmixed purple zones remaining); brown color appears *only after* droplet contact and *coincides with shaking*; no reversion to purple or fading during video.
level_5: All elements from 4-score are satisfied, and the brown state exhibits *continuous visual evolution*: initial purple → transient mottling (purple/brown intermixing) → fully homogeneous brown; no frame shows isolated purple islands or sharp purple-brown boundaries after shaking begins; brown suspension is visibly *colloidal* (hazy, non-settled, no large aggregates).

Spatiotemporal Consistency rubric:
level_1: The beaker's contents or the beaker itself change appearance instantaneously between two consecutive frames with no transition at all — for example, the solution is purple in one frame and fully brown in the very next with no shaking or mixing shown; a droplet is shown entering the solution from the dropper, then in the next frame the same droplet reads as simultaneously still falling and already dissolved, as if two contradictory moments were shown at once; the beaker's silhouette changes shape or size between frames as if it were a different container entirely; or the room's lighting swings abruptly between bright and dark with no lamp, switch, or other visible cause in the shot.
level_2: A droplet's position jumps from partway down its fall to already resting inside the solution, skipping the portion of its path where it would cross the solution's surface; the beaker jumps to a distant new position or leaves and re-enters the frame with no connecting motion, rather than moving through a visible shaking path; the purple-to-brown color change happens in one abrupt frame-to-frame jump instead of appearing progressively while the beaker is shaken.
level_3: Minor but real flaws are tolerated: one brief freeze or stutter in the shaking motion; the beaker's oscillation is uneven or fades out partway through instead of continuing steadily for the rest of the clip; the purple-to-brown transition is mostly gradual but includes one visibly abrupt jump in hue partway through the shaking.
level_4: All elements from 3-score are present AND the droplet's fall from the dropper tip to the solution surface follows one smooth, unbroken path; the shaking motion is continuous back-and-forth with no freezing or skipped frames; the beaker's side-to-side shaking motion stays smooth and repeating, with no sudden teleporting jumps in position and no change in the beaker's size or shape at any point in the clip; the purple-to-brown transition unfolds gradually across multiple frames of visible mottling rather than jumping straight to the end state.
level_5: All elements from 4-score are present AND the beaker's size stays constant and its shaking motion remains smooth and rhythmic from the first frame to the last, with the camera viewpoint fixed and centered throughout; the solution's surface sloshes and settles in a way that visibly matches the beaker's shaking motion frame to frame; the purple-to-brown color change tracks continuously with the shaking (more of the solution turns brown the longer shaking continues, and it never reverts to purple); no frame in the clip is a frozen or duplicated copy of an earlier one.