Domain: Natural Science — Chemistry
Target concept: Glucose decolorizes potassium permanganate.

Video generation prompt: A test tube containing an appropriate amount of potassium permanganate solution was treated with an appropriate amount of glucose solution.

Evaluation guide:
(i) Target concept: Reductive decolorization of potassium permanganate by glucose in aqueous solution.
Minimum mechanism: Glucose must be in direct liquid-phase contact with dissolved KMnO4 under conditions permitting electron transfer; no catalyst or heat required for observable slow decolorization at room temperature; the reaction proceeds without gas evolution, precipitation, or intermediate color formation (e.g., MnO2 brown precipitate is excluded; this implies acidic conditions, since only acidic conditions reduce Mn(VII) all the way to colorless Mn2+; neutral or mildly basic conditions instead stop at brown MnO2, which is not observed here).
(ii)Storyline: [Frame 0–2] Static shot: upright test tube filled ~1/2 with homogeneous purple liquid (KMnO4 solution); [Frame 3–4] Dropper/pipette enters from top, dispenses colorless liquid (glucose solution) into the tube; [Frame 5–6] First visible contact between liquids: meniscus disturbance and mixing initiation; [Frame 7–9] Purple color recedes progressively (e.g., from contact zone outward or top-down); [Frame 10] Final state: fully homogeneous, transparent, colorless liquid filling same volume; viewpoint remains fixed side-on; no occlusion; all events unfold in single continuous take.

Manual:
Experimental Procedure
1. A clear test tube contains a purple potassium permanganate (KMnO4) aqueous solution.
2. A colorless glucose solution is added to the test tube.
3. The two solutions mix (via gentle swirling or dropper delivery).
Observation of Experimental Phenomena
The initial purple color of the KMnO4 solution fades completely, resulting in a colorless (decolorized) solution.
Summary of Experimental Principles
Glucose acts as a reducing agent, decolorizing purple KMnO4 by reducing Mn(VII) to Mn(II) under acidic conditions — a characteristic redox reaction.

Prompt Grounding rubric:
level_1: Neither the test tube nor the purple potassium permanganate (KMnO4) solution nor the glucose solution appears anywhere in the video; no liquid is added to another liquid.
level_2: A test tube appears, but the KMnO4 solution is not shown as a purple liquid, or the glucose solution is not shown as a colorless liquid, or no addition/mixing action between the two liquids ever takes place; alternatively, glucose solution appears in the tube before the purple KMnO4 solution is established.
level_3: The test tube holds a purple KMnO4 solution first; a colorless glucose solution is then introduced into the same tube; a mixing action (dropper delivery or swirling) is shown; the three required elements (test tube, purple KMnO4 solution, glucose solution) and their correct order (KMnO4 first, then glucose) are all present.
level_4: Everything required for score 3 holds, and in addition the test tube stays in place for the whole clip, both liquids stay inside the tube during and after mixing, no unrelated objects (extra beakers, hands, labels) share the frame, and the camera keeps a fixed side-on framing that shows the liquid interface clearly.
level_5: Everything required for score 4 holds, and in addition the whole sequence plays as one uninterrupted shot, the test tube's position and tilt do not change, the glucose solution visibly enters from a dropper or pipette tip coming from above the frame, the liquid column is never blocked from view, and there is no flicker, blur, or transparency glitch that breaks the sense of a single continuous tube and liquid.

Scientific and Causal Correctness rubric:
level_1: The purple color of the KMnO4 solution never changes; or it changes to a color other than colorless (green, brown, blue, or a cloudy precipitate); or the solution turns colorless before any glucose solution has touched it.
level_2: The purple KMnO4 solution is shown, but decolorization is incomplete (e.g., the top of the liquid clears while the bottom remains purple), happens before the glucose solution makes contact, or ends in the wrong color (pink or yellow rather than colorless); or the color loss looks instantaneous with no visible transition, or is paired with bubbles or a precipitate that don't belong in a glucose–KMnO4 reaction.
level_3: The purple KMnO4 solution is clearly visible before the glucose solution is added; once the glucose solution contacts it, the purple color visibly fades to a fully colorless (or essentially colorless) liquid; no precipitate, gas bubbles, or layer separation appear at any point.
level_4: Everything required for score 3 holds, and in addition the fading only starts once the two liquids are shown touching (not before), the finished liquid is colorless all the way through with no purple streaks or patches left behind, and nothing about the lighting or framing (dimming, vignette, filter-like fade) is doing the work of a color change that isn't chemically real.
level_5: Everything required for score 4 holds, and in addition the purple color recedes in one steady direction (for example spreading outward from where the glucose solution entered, or fading from top to bottom) without pausing, reversing, or flashing back, the colorless end state holds steady for at least a second before the clip ends, and there's no meniscus distortion or odd refraction that would make a viewer think the tube still has two unmixed layers.

Spatiotemporal Consistency rubric:
level_1: The test tube vanishes and reappears, or the liquid inside it jumps to a different level or position between frames; the tube's size, tilt, or place in the frame suddenly changes without any matching motion; the video cuts mid-action; the tube appears cracked, bent, or hollow when it should be intact; or the lighting flips abruptly between very different brightness levels with no cause.
level_2: The test tube stays visible but something breaks continuity in a major way: heavy motion blur hides what the liquid is doing, the image flickers or strobes, the shadow cast by the tube swings to a different direction between frames, the liquid surface keeps rippling without ever settling, or the background shifts or zooms for no reason.
level_3: The test tube stays visible and intact for the whole clip; the liquid surface is calm during still moments and only moves in plausible ways (a small ripple when the glucose solution is added, settling afterward); the tube's shadow keeps a steady direction and strength; there is no cut, no jump in the tube's position, and the tube never changes shape.
level_4: Everything required for score 3 holds, and in addition the motion makes physical sense: the dropper comes down and pulls back along a straight vertical path, added liquid flows downward rather than floating, the liquid column never stretches or squashes unnaturally, and the framing and perspective stay the same in every frame.
level_5: Everything required for score 4 holds, and in addition the motion feels evenly paced from frame to frame with no sudden jumps in speed, the liquid surface settles back smoothly after being disturbed, the edge of the tube and the liquid meniscus stay sharp and steady rather than shimmering or wobbling, and the dropper's movement and the moment the liquid actually makes contact stay in sync rather than looking out of step.