Domain: Natural Science — Chemistry
Target concept: Bromine Water Test: Comparative Reactivity of Benzene and Cyclohexene

Video generation prompt: Two transparent flasks are placed side by side on the laboratory bench: the left one contains benzene, and the right one contains cyclohexene. An equal amount of orange bromine water is added to each flask, and the flasks are gently shaken.

Evaluation guide:
(i) Target concept: Visual differentiation of unsaturation reactivity via bromine water decolorization.
Minimum mechanism: Bromine water must be orange pre-reaction; cyclohexene must contain an accessible C=C bond for rapid addition; benzene must remain inert due to aromatic stability; the reaction must require mechanical agitation to initiate contact; no catalyst or UV light is involved. Because both benzene and cyclohexene are immiscible with water, each flask will settle into two visible liquid layers (the aqueous bromine water and the organic solvent) once shaking stops; this layering is a normal, expected physical outcome and is not itself evidence of an incorrect reaction.
(ii)Storyline: Frame opens on static bench with two labeled transparent flasks side-by-side → bromine water poured into both flasks (synchronously, visibly orange) → flasks shaken simultaneously (continuous, gentle motion) → motion stops → flasks settle into their aqueous and organic layers → left (benzene) flask remains orange somewhere in its liquid, right (cyclohexene) flask is uniformly colorless throughout; all events occur from a fixed frontal lab-bench viewpoint with full flask visibility and no occlusion.

Manual:
Experimental Procedure
1. Place two transparent flasks side-by-side on the bench: left contains benzene, right contains cyclohexene.
2. Add an equal volume of orange bromine water to each flask.
3. Gently shake both flasks simultaneously, then let them stand briefly.
Observation of Experimental Phenomena
After shaking, each flask settles into two liquid layers (aqueous bromine water and organic solvent), since both benzene and cyclohexene are immiscible with water — this layering is expected in both flasks. Left flask (benzene): orange color persists in the liquid overall. Right flask (cyclohexene): the liquid becomes completely colorless.
Summary of Experimental Principles
Benzene does not undergo electrophilic addition with bromine under dark, aqueous conditions, so Br₂ is not consumed and the flask stays orange; cyclohexene rapidly decolorizes bromine water via electrophilic addition across its C=C bond, consuming the Br₂ and leaving both layers colorless.

Prompt Grounding rubric:
level_1: No two flasks are shown together in the same shot, or the flasks aren't transparent, or no orange bromine water is added to either flask, or the flasks aren't identified as containing benzene and cyclohexene, or neither flask is shaken.
level_2: Two transparent flasks sit next to each other, but at least one setup detail is missing: the left flask isn't identifiable as benzene, the right flask isn't identifiable as cyclohexene, orange bromine water isn't visibly added to both, or shaking isn't applied to both.
level_3: Two transparent flasks sit side by side in the same shot; the left one is identifiable as benzene and the right one as cyclohexene (by label, on-screen text, or another clear visual cue); orange bromine water is visibly added to both; both flasks are then visibly shaken, all within one continuous shot.
level_4: Everything required for score 3 is shown, and in addition: neither flask changes position, rotates, or gets blocked from view between the addition and the settled aftermath; the bromine water is added to both flasks at essentially the same time; both flasks are shaken together, not one after the other.
level_5: Everything required for score 4 is shown, and in addition: there is no camera cut, zoom, or angle change for the whole sequence; both flasks stay fully visible and uncropped, without blur that hides which flask is which or what's inside it; the flasks, liquids, and labels keep a consistent look throughout (nothing flickers, gets replaced, or morphs into something else).

Scientific and Causal Correctness rubric:
level_1: Neither flask changes color; or both flasks change color the same way; or any color change happens before the flasks are shaken; or the bromine water isn't orange to begin with.
level_2: One flask changes color, but the wrong way round: the benzene (left) flask fades toward colorless, or the cyclohexene (right) flask stays orange, or both fade, or the fading happens before shaking, or a color change shows up in a solid or in vapor above the liquid rather than in the liquid itself.
level_3: After shaking, the benzene flask (left) is still visibly orange somewhere in its liquid, and the cyclohexene flask (right) has lost essentially all its orange color; both results are stable and don't change further once shaking stops.
level_4: Everything required for score 3 holds, and in addition: the cyclohexene flask ends up completely colorless with no orange tint left in either layer; the benzene flask shows no fading or streaking of its orange color in either layer; neither flask ever shows an intermediate color like brown or yellow-green.
level_5: Everything required for score 4 holds, and in addition: the cyclohexene flask's color loss finishes right around when the shaking stops, without lingering afterward or finishing early; the benzene flask's orange color and brightness look the same after shaking as before. Each flask settling into two visibly distinct liquid layers (aqueous bromine water and organic solvent) after shaking is expected and is not itself counted against either flask; what would count against a flask is the orange color ending up concentrated in a layer inconsistent with the described reaction (e.g., the cyclohexene flask keeping strong orange color in its organic layer, or the benzene flask's organic layer going completely colorless while its aqueous layer stays deep orange in a way that suggests unexpected extraction), or new phenomena such as gas bubbles or a solid precipitate appearing in either flask.

Spatiotemporal Consistency rubric:
level_1: A flask jumps to a new spot between frames; a flask's size or shape suddenly changes; the lighting jumps abruptly (e.g., a shadow disappears then reappears); a flask's edge warps or cracks; or the liquid surface inside a flask jumps or breaks apart between frames.
level_2: At least one clear motion problem: bromine water appears in a flask instantly with no pouring motion shown; the shaking motion skips or jumps rather than flowing continuously; one flask rotates while the other stays still; or a label shifts position relative to its flask partway through.
level_3: Neither flask jumps position, cracks, or is affected by a sudden lighting change; the liquid surface moves continuously while being shaken; the two flasks stay in the same position relative to each other; all motion looks physically reasonable (nothing floats, freezes mid-motion, or moves impossibly rigidly).
level_4: Everything required for score 3 holds, and in addition: the motion between frames is smooth with no stutter, ghosting, or repeated frames; the liquid surface in each flask moves the way a real meniscus would while being shaken (not sliding as a rigid block or flowing backward); both flasks obey the same perspective and don't drift out of alignment with each other.
level_5: Everything required for score 4 holds, and in addition: there's no jitter or wobble in either flask between frames; once the shaking stops, any remaining liquid movement settles down naturally rather than sloshing indefinitely; both flasks keep a consistent depth relationship with the bench surface (neither appears to float above or sink below it); the bromine water is never shown being added after the shaking has already started.