Domain: Natural Science — Chemistry
Target concept: Tollen's test comparison: Aldehydes produce a silver mirror, while ketones show no significant reaction.

Video generation prompt: Two transparent test tubes are placed side by side in a water bath. Tollens' reagent is added to both test tubes, and then a colorless aldehyde is added to the left tube, while a colorless ketone is added to the right tube. The tubes are gently shaken.

Evaluation guide:
(i) Target concept: Selective redox reactivity of carbonyl compounds with Tollens' reagent.
Minimum mechanism: Presence of aqueous [Ag(NH₃)₂]⁺ complex, alkaline conditions, and thermal activation in the water bath; the left-tube reagent must carry an aldehyde group (R-CHO, e.g., formaldehyde or acetaldehyde), which Tollens' reagent oxidizes to a carboxylate while reducing Ag⁺ to metallic Ag; the right-tube reagent must be a ketone (e.g., acetone), which has no oxidizable aldehyde hydrogen and therefore produces no mirror.
(ii)Storyline: Frame 0–2: Static shot of two empty transparent tubes side-by-side in water bath → Frame 3–4: Dropper adds clear Tollens' reagent to both tubes → Frame 5–6: Second dropper adds colorless aldehyde to left, colorless ketone to right → Frame 7–8: Hands gently shake both tubes synchronously → Frame 9–10: Left tube reveals uniform silver mirror; right tube retains pristine clarity. Fixed frontal viewpoint; full tubes always in frame; no occlusion; lighting consistent; no zoom or pan.

Manual:
Experimental Procedure
1. Place two identical transparent test tubes side-by-side in a warm water bath.
2. Add Tollens" reagent to both tubes.
3. Add a colorless aldehyde to the left tube and a colorless ketone to the right tube.
4. Gently shake both tubes simultaneously.
Observation of Experimental Phenomena
Left tube develops a continuous, reflective silver mirror on inner wall; right tube remains fully clear and unchanged.
Summary of Experimental Principles
Aldehydes reduce Ag⁺ in Tollens" reagent to metallic Ag, forming a silver mirror; ketones do not undergo this oxidation-reduction reaction and thus show no visible change.

Prompt Grounding rubric:
level_1: Fewer than two test tubes appear, the water bath is absent, Tollens' reagent is never added to either tube, or the two tubes are stacked, widely separated, or otherwise not shown next to each other.
level_2: Two test tubes and a water bath are both present and shown next to each other, but at least one required element is incomplete: Tollens' reagent is added to only one of the two tubes, the substances added afterward to the two tubes cannot be told apart at all, or one tube is not actually immersed in the water bath.
level_3: Two test tubes sit side by side in a water bath; Tollens' reagent is visibly dispensed into both; a colorless liquid is then added to the left tube and a colorless liquid to the right tube, but nothing in the video (label, dropper color, on-screen text) tells the viewer which tube received the aldehyde and which received the ketone.
level_4: All of score 3, plus the left tube is identifiable as the aldehyde tube and the right tube as the ketone tube through a label, caption, or other unambiguous visual cue, the order of additions matches the prompt (Tollens' reagent first, then aldehyde/ketone), and every object named in the prompt [two tubes, water bath, dropper(s)] appears with no extras added.
level_5: All of score 4, plus the left/right identity of the tubes never becomes ambiguous (neither tube is rotated, swapped, or repositioned after being identified), both tubes stay fully in frame for the whole clip, and the camera holds one fixed framing on both tubes without zooming or panning away from either one.

Scientific and Causal Correctness rubric:
level_1: Neither tube ever develops a silver mirror, or both tubes end up looking the same as each other (both mirrored or both unchanged), so the video shows no differentiation between the aldehyde and ketone tubes.
level_2: Exactly one tube develops a mirror-like coating, but it is the right (ketone) tube rather than the left (aldehyde) tube, or a dull, non-reflective deposit forms in one or both tubes without an actual mirror forming.
level_3: A mirror-like coating forms on the left tube only and the right tube stays clear, but the coating is patchy or covers only part of the tube wall, or the right tube shows cloudiness that a ketone should not produce.
level_4: All of score 3, plus the left tube's coating is continuous and covers the wall fully, the right tube shows no haze, deposit, or color change of any kind, and neither tube shows an event (boiling, foaming, unrelated color shift) that these reagents would not produce.
level_5: All of score 4, plus the left tube's mirror has a uniform metallic sheen from the liquid line to the tube bottom, the right tube's liquid looks exactly as clear at the end as it did before Tollens' reagent was added, and the mirror only becomes visible during or after the shaking step, not before shaking or after the tubes leave the water bath.

Spatiotemporal Consistency rubric:
level_1: A tube or the water bath vanishes and reappears, a tube's position or tilt jumps between frames with no shaking motion shown, a dropper appears at a tube's mouth with no visible approach, or the lighting abruptly flips between bright and dark from one moment to the next with no in-scene cause.
level_2: The tubes shift sideways or their spacing changes between the reagent-adding step and the aldehyde/ketone-adding step, the water bath's liquid level changes with no visible cause, or the silver mirror appears fully formed in a single frame with no gradual buildup shown across the shaking motion.
level_3: The tubes and water bath stay in the same place and orientation from the first frame to the last; the reagent addition, the aldehyde/ketone addition, and the shaking are each shown as one continuous action rather than a cut; brief camera wobble or soft focus is acceptable as long as both tubes stay visible.
level_4: All of score 3, plus each dropper visibly travels toward its tube before releasing liquid, the shaking motion looks the same speed and range for both tubes at once, and the tube walls keep the same curvature and thickness in every frame.
level_5: All of score 4, plus both tubes shake with matching amplitude and timing, the liquid line in each tube stays level and moves together during shaking, and reflections on the glass shift smoothly with the light source rather than jumping or smearing between frames.