Domain: Natural Science — Chemistry
Target concept: Orange-yellow bromine water rapidly decolorizes to colorless, with no precipitate or gas formation.

Video generation prompt: Add bromine water to ethyl acetoacetate and shake gently while recording the mixture.

Evaluation guide:
(i) Target concept: Electrophilic addition of bromine to an active methylene compound (ethyl acetoacetate) resulting in instantaneous, stoichiometric decolorization.
Minimum mechanism: Bromine (Br₂) must be molecularly dissolved in aqueous or dilute solvent; ethyl acetoacetate must be neat or in inert solvent; no catalyst, light, or heat required; reaction proceeds at room temperature via enol tautomer attack on Br₂.
(ii)Storyline: [Frame 0–2] Two distinct clear containers in fixed side-by-side arrangement: left contains colorless liquid (ethyl acetoacetate), right contains orange-yellow liquid (bromine water). [Frame 3–4] Right container lifted and tilted; orange-yellow liquid flows continuously into left container. [Frame 5–6] Combined liquid fills left container; no splashing or overflow. [Frame 7–9] Left container undergoes gentle horizontal oscillation (shaking); orange-yellow color visibly diminishes across entire liquid volume. [Frame 10] Final frame shows fully colorless, transparent, homogeneous liquid; no residue, no bubbles, no turbidity. All events occur within single unbroken shot, fixed viewpoint, consistent lighting, and no occlusion.

Manual:
1. Experimental Procedure: Place a clear container with colorless ethyl acetoacetate beside a second clear container with orange-yellow bromine water. Pour bromine water into ethyl acetoacetate container. Gently shake the mixture for ~2 seconds.
2. Observation of Experimental Phenomena: Bromine water rapidly decolorizes from orange-yellow to colorless upon shaking; no precipitate forms; no gas bubbles appear; solution remains homogeneous and transparent.
3. Summary of Experimental Principles: Ethyl acetoacetate contains an active methylene group that undergoes rapid electrophilic addition with bromine, consuming Br₂ and causing decolorization without byproducts.

Prompt Grounding rubric:
level_1: No container of bromine water and no container of ethyl acetoacetate appear on screen; no pouring or shaking of either liquid is shown.
level_2: Only one of the two liquids (bromine water or ethyl acetoacetate) is shown in a container, with no contact between them; no shaking motion of any container occurs.
level_3: A container of orange-yellow bromine water and a container of colorless ethyl acetoacetate are both visible; the bromine water is poured into the ethyl acetoacetate container; the combined liquid is then shaken by hand; the pour and the shake both appear, in that order.
level_4: All of score 3, plus: the two containers sit side-by-side before the pour and only one combined container remains afterward; shaking begins only once the pour has fully finished; no extra steps appear (no stirring rod, no heating, no second addition of either liquid).
level_5: All of score 4, plus: the bromine-water container is shown lifted and tilted so the pour's start and finish are both visible with no cut in between; the shaking starts right as the pour ends; both containers stay fully in frame for the whole clip with no repositioning or camera cut between the pour and the shake.

Scientific and Causal Correctness rubric:
level_1: The orange-yellow color of the bromine water never fades: it stays orange-yellow to the end, or the ethyl acetoacetate itself is shown taking on color instead of the bromine water losing it; no decolorization is shown at all.
level_2: The bromine water's color changes to something other than colorless (e.g., pale yellow, green, or brown), or it decolorizes before ever touching the ethyl acetoacetate, or the color is already gone before the shaking starts.
level_3: The orange-yellow bromine water, once poured into the ethyl acetoacetate and shaken, becomes colorless with no precipitate and no gas bubbles forming; the color loss only begins once shaking is underway and stays gone for the rest of the clip.
level_4: All of score 3, plus: the color fades smoothly rather than in an abrupt jump or flash, the whole liquid volume turns colorless together rather than leaving streaks of orange behind in part of the mixture, and nothing else appears in the liquid (no cloudiness, no bubbling, no separate layers).
level_5: All of score 4, plus: the bromine water's orange-yellow color is clearly strong and unambiguous at the very start, the end state is unmistakably colorless with no lingering tint, and the fading tracks with the shaking (starting once shaking begins, stopping once it stops) with no color returning partway through.

Spatiotemporal Consistency rubric:
level_1: Either container disappears and reappears somewhere else on screen, the liquid inside changes shade abruptly for reasons unrelated to the reaction (e.g., a sudden lighting cut from bright to dark), frames are missing so the pour appears to start in mid-air, or a container visibly cracks or leaks in a way that doesn't match the gentle handling shown.
level_2: A container shifts by more than about a third of the frame's width between shots, a visible cut interrupts the pour or the shake partway through, the shadow cast by a container points a different way before and after a cut, or the liquid's surface resets to a flat, undisturbed state abruptly during shaking.
level_3: Both containers stay visible and in roughly the same place throughout; the pour and the shake both move at a natural, gradually changing speed rather than at constant or jerky speed; there are no visible cuts and neither container vanishes at any point; the liquid surface tilts and settles the way a real liquid would while being shaken.
level_4: All of score 3, plus: the shake stays a gentle back-and-forth motion rather than swirling or splashing hard, the container never lifts off the surface or spins out of its upright orientation, and the liquid's surface moves in time with the visible hand motion rather than lagging or leading it.
level_5: All of score 4, plus: the back-and-forth shaking keeps the same width and speed from start to finish, the container's base stays touching the surface the whole time, and the liquid's surface moves as one connected wave rather than breaking into separate splashes or freezing mid-motion.