Domain: Healthcare — Pharmaceutical Chemistry
Target concept: Condensation Reaction of Drugs (Aldol Condensation)

Video generation prompt: Take a small amount of acetaldehyde and acetone, mix them in a test tube in a 1:1 volume ratio, add one drop of sodium hydroxide solution as a catalyst, shake well, and place at room temperature. Observe the changes in the solution's appearance and let it stand for 3 seconds.

Evaluation guide:
(i) Target concept: Base-catalyzed cross-aldol condensation between acetaldehyde and acetone yielding a water-insoluble α,β-unsaturated ketone (pent-3-en-2-one) that manifests as colloidal turbidity.
Minimum mechanism: Catalyst must be present *before* condensation; enolate formation requires strong base (NaOH); acetone (enolizable at its alpha carbons) forms the nucleophilic enolate and attacks the more electrophilic, less hindered carbonyl carbon of acetaldehyde, giving the aldol addition product 4-hydroxy-2-pentanone, which then dehydrates to pent-3-en-2-one; product must be hydrophobic enough to phase-separate as sub-micron particles, not macroscopic precipitate or oil layer.
(ii)Storyline: [Frame 0–2] Two distinct reagent containers (clear liquids, identical appearance but labeled) sit adjacent in fixed viewpoint. [Frame 3–4] Equal-volume transfer into central test tube (liquid menisci align visually). [Frame 5] Dropper tip positioned above test tube; single spherical droplet detaches and falls. [Frame 6–7] Hand grips test tube and performs rapid vertical oscillation (shaking). [Frame 8] Hand releases; test tube settles upright. [Frame 9–11] Absolute stillness: turbidity emerges homogeneously within liquid column; no motion, no settling, no interface change. Visibility constraint: entire sequence viewed frontally at fixed distance; test tube never occluded; all labels legible; lighting diffuse and shadow-consistent.

Manual:
Experimental Procedure
1. Place two labeled reagent containers (acetaldehyde, acetone) side-by-side.
2. Transfer equal volumes into a clean test tube (1:1 ratio).
3. Add one drop of sodium hydroxide solution using a dropper.
4. Shake test tube vigorously by hand.
5. Place test tube upright and hold motionless for 3 seconds.
Observation of Experimental Phenomena
A uniform milky-white turbidity appears in the solution during stillness — no color change, no precipitation settling, no gas evolution.
Summary of Experimental Principles
Acetaldehyde and acetone undergo base-catalyzed aldol condensation: acetone (enolizable at its alpha carbons) forms the enolate and attacks the more electrophilic, less hindered carbonyl carbon of acetaldehyde, yielding 4-hydroxy-2-pentanone, which dehydrates to pent-3-en-2-one — the unsaturated product causes colloidal turbidity due to low aqueous solubility.

Prompt Grounding rubric:
level_1: No test tube is shown; or neither the acetaldehyde container nor the acetone container is visible; or no drop of sodium hydroxide solution is shown being added; or no shaking motion is depicted at all; or the test tube is never shown standing still afterward.
level_2: A test tube containing liquid is shown, but only one of the two reagents (acetaldehyde or acetone) has a container visible; or no NaOH drop is added before the tube is shaken; or the mixing step is shown as pouring or swirling rather than hand-shaking; or the tube is never held still after mixing.
level_3: Two separate reagent containers (one for acetaldehyde, one for acetone) are shown side by side; equal volumes from each are transferred into a single test tube; one drop of NaOH solution is added; the tube is then shaken by hand; the tube is subsequently held stationary; all objects (the two reagent containers, the dropper, the test tube) match the types named in the prompt.
level_4: Everything required for the 3-point level is present, and in addition the acetaldehyde and acetone containers are visually distinguishable from each other (e.g., different labels or container shapes) so the two reagents are never confused; the NaOH drop is added and the tube is shaken only afterward, preserving the order mix -> add NaOH -> shake -> stillness; and the same test tube stays in view throughout rather than being swapped for a different container.
level_5: Everything required for the 4-point level is present, and in addition exactly one NaOH drop is shown leaving the dropper and entering the tube (not a stream, splash, or mist); the shaking is visibly hand-driven back-and-forth or up-and-down agitation rather than gentle swirling; and after shaking stops the tube is held still for a clear, unmistakable pause of about 3 seconds (matching the prompt's stand time), not just a brief pause or an instant cut.

Scientific and Causal Correctness rubric:
level_1: No turbidity, cloudiness, or precipitate ever appears: the liquid in the test tube stays completely clear and colorless from start to finish.
level_2: Some visible change occurs, but it is the wrong kind or wrong timing for a base-catalyzed aldol condensation: e.g., the liquid visibly bubbles or gives off gas, the liquid darkens to brown or black instead of turning milky white, or cloudiness appears before the NaOH drop is added or before the shaking happens.
level_3: A milky-white turbidity appears in the test tube only after the NaOH drop has been added and the shaking has stopped; the liquid does not bubble, does not turn yellow or brown, and does not separate into distinct layers.
level_4: Everything required for the 3-point level is present, and in addition the turbidity does not appear at all until after both the NaOH drop and the shaking have occurred (never partway through shaking and never before the drop lands), and once it appears it stays visible continuously, without fading, flashing, or disappearing and reappearing during the still period.
level_5: Everything required for the 4-point level is present, and in addition the turbidity looks like a fine, uniform suspension spread evenly through the entire liquid column rather than clumps floating on top or a layer settled at the bottom; it appears right as the shaking stops rather than several seconds later; and it stays just as cloudy for the whole still period without settling out, clearing up, or separating.

Spatiotemporal Consistency rubric:
level_1: The test tube, either reagent container, or the hand vanishes from view and reappears later in the clip; the test tube's position or tilt jumps suddenly between two consecutive frames with no motion shown in between; the room's brightness changes abruptly with no flame, light switch, or other visible cause; or the test tube's glass appears to crack, bend, or reshape on its own.
level_2: A container or the test tube flickers out of view for a couple of frames during the shaking and then returns; the shadow cast by the hand or tube swings to a different side than where the light is coming from; the tube's outline looks slightly warped while it is being shaken; or a visible jump or splice interrupts the clip partway through.
level_3: The test tube stays centered and upright in the same spot on screen for the whole clip; the two reagent containers stay in the same place relative to the tube; the hand enters and leaves the frame smoothly rather than popping in or out; the shadows cast by the tube and hand point in one consistent direction the whole time; nothing about the tube or containers bends, stretches, or gets clipped by the frame edge.
level_4: Everything required for the 3-point level is present, and in addition the shaking motion itself flows smoothly from start to end with no sudden jump-cuts or freezes; the drop of NaOH solution falls along one continuous visible path rather than skipping partway; and once shaking ends the tube truly stops moving: no small vibrations, drifting, or bobbing during the still period.
level_5: Everything required for the 4-point level is present, and in addition the hand's shaking motion looks like a natural human arm and wrist swing rather than a mechanical repeat; the falling NaOH drop follows a believable gravity-curved path down into the tube; the base of the test tube stays planted on the same spot on the table the entire time; and every reflection of light on the glass tube shifts in a way that matches the hand's and tube's own motion rather than looking pasted on.