Domain: Healthcare — Nutrition & Dietetics
Target concept: Honey contains reducing sugars, as evidenced by the formation of a brick-red precipitate when its aqueous solution is heated with Fehling's reagent.

Video generation prompt: Place the honey solution into a test tube, add Fehling's reagent, gently mix, and then place the test tube in a water bath for heating. Demonstrate clean glassware, Fehling's reagent, controlled heating process, and step-by-step procedures performed in the correct order.

Evaluation guide:
(i) Target concept: Visual demonstration of reducing sugar detection via Fehling"s test in honey.
Minimum mechanism: Reducing sugars must be present in solution; Fehling"s reagent must be freshly prepared and alkaline; heating must be sufficient to drive redox reaction; Cu₂O formation must occur and remain insoluble to yield visible precipitate.
(ii)Storyline: [Frame 0–2] Clean test tube centered, honey solution poured in (amber, viscous, meniscus visible). [Frame 3–4] Fehling"s reagent bottle enters right frame, dispenses deep blue liquid into same test tube. [Frame 5–6] Hand swirls test tube → homogeneous deep blue mixture forms. [Frame 7–8] Test tube lowered vertically into water bath → full immersion achieved; water surface ripples gently. [Frame 9–10] Brick-red granular precipitate emerges uniformly within solution, settling slowly; supernatant remains translucent blue. All events occur in fixed frontal view with no cuts, no occlusion, and consistent lighting.

Manual:
Experimental Procedure
1. Place clear amber honey solution into clean test tube.
2. Add equal volume of deep blue Fehling"s reagent.
3. Gently swirl test tube to mix.
4. Immerse test tube fully in warm water bath.
Observation of Experimental Phenomena
Deep blue mixture turns to brick-red precipitate during heating; precipitate appears as granular solid particles, distinct from liquid supernatant.
Summary of Experimental Principles
Honey contains reducing sugars (e.g., glucose, fructose) that reduce Cu²⁺ in alkaline Fehling"s reagent to Cu₂O, forming a characteristic brick-red precipitate.

Prompt Grounding rubric:
level_1: No test tube appears, no honey solution is visible, no Fehling's reagent bottle or blue liquid is shown, no water bath is present, and no hand or tool carries out any step.
level_2: One relevant object shows up (the test tube, or the reagent bottle, or the water bath) but the required actions do not: honey is never placed in the tube, the reagent is never added, no mixing takes place, and the tube is never heated in a water bath; the step order is missing entirely or runs backward.
level_3: A test tube, an amber honey solution, a bottle of deep-blue Fehling's reagent, and a water bath with warm water (steam or a gentle surface ripple visible) are all present; honey goes into the tube, then the reagent is added to the same tube, then the tube is swirled or tilted to mix, then it is lowered into the water bath; the four steps occur in that order without any skipped.
level_4: All elements of score 3 are present AND the tube stays upright while being mixed; the reagent bottle is held right next to the tube while dispensing; the water bath sits in a fixed spot in the lower part of the frame; no object drops out of the shot or appears suddenly between steps; the tube used for mixing is the same one that goes into the bath.
level_5: All elements of score 4 are present AND the test tube keeps the same shape, size, and color from first frame to last; the honey keeps the same amber, viscous look throughout; the Fehling's reagent keeps the same deep-blue color and clarity before it's added; the water bath keeps the same depth and shows the same gentle surface motion the whole time; there is no camera cut, zoom, or angle change breaking the single fixed viewpoint, and each action is carried out in one smooth, deliberate motion.

Scientific and Causal Correctness rubric:
level_1: No color change happens at all, or the mixture ends up black, dark brown, or stays deep blue with nothing precipitating; a brick-red solid never appears at any point; there's no sign that heating is happening or has happened; the outcome contradicts what reducing sugars in honey should do to Fehling's reagent.
level_2: A color change happens but the end color isn't brick-red (e.g., the precipitate stays green or yellow with no further progression, or brick-red material shows up before any heating is visible, or before the reagent has even been added), breaking the expected add-reagent-then-heat-then-precipitate order.
level_3: A brick-red precipitate appears only once heating is underway; it forms as discrete grainy or flocculent particles rather than a smooth film; the mixture visibly starts out deep blue before heating begins; the water bath is visibly active (tube submerged, water clearly warm) when the precipitate appears; the honey solution may pass through a yellow or green intermediate on its way to brick-red, or go straight to brick-red; either is acceptable, but no other final color (black, brown, unchanged blue) is present.
level_4: All elements of score 3 are present AND the precipitate only shows up after the tube has been in the water bath for a visible stretch of time, not the instant it goes in; some blue supernatant is still visible above the settling precipitate rather than the mixture being fully decolorized; there's no unrelated distraction like boiling-over, charring, or a hazy film unconnected to the reduction reaction; the final solid reads unambiguously as brick-red rather than orange, rust, or pink.
level_5: All elements of score 4 are present AND the precipitate looks like fine granular or flocculent particles, not a gel or a surface film; the particles settle downward under their own weight rather than floating; once the particles are red they stay a uniform brick-red with no lingering patches of the intermediate green or yellow color; if a yellow or green intermediate stage appears on the way to red, it is transient and fully resolves to a consistent brick-red rather than persisting alongside the red particles.

Spatiotemporal Consistency rubric:
level_1: Severe breaks: the test tube vanishes from one frame and reappears in a different spot in the next; liquid spurts out of the tube with no physical cause; the lighting swings from bright daylight to near-darkness within a couple of frames; the tube appears to crack and then looks intact again; motion freezes or stutters for more than a second, long enough that the video feels like it has stalled.
level_2: Several moderate problems appear together: the shadow the tube casts points a different way at different steps with no change in the light; the water bath's surface looks still, then suddenly ripples with no cause; the swirling motion stops dead and restarts identically a moment later; the tube rotates by more than 90 degrees with no hand or tool touching it; the frame brightens or dims noticeably right as the tube is heating.
level_3: The test tube stays centered in the lower part of the frame; the water bath stays put in the background; the reagent bottle enters from one consistent side and leaves cleanly after dispensing; nothing on screen flickers, vanishes, or doubles up; the swirling and lowering-into-the-bath motions run smoothly with no jump in position; the overall lighting looks the same from the first frame to the last.
level_4: All elements of score 3 are present AND the swirl-to-immersion transition flows directly with no gap; the water bath's visible steam or ripple only appears once the tube is fully submerged, not before; the brick-red precipitate starts forming only once the water bath is clearly active, not immediately at first contact; the mixing motion doesn't overlap with the tube already being underwater.
level_5: All elements of score 4 are present AND there's no sudden jerk or blur inconsistent with the tube's actual speed of movement; the tube in the foreground and the water bath behind it move together with no apparent mismatch; every stage (pour, add reagent, mix, immerse, heat, precipitate) flows into the next through continuous motion rather than a hard cut; the camera holds its position the whole time with no visible refocusing or exposure jump.