Domain: Natural Science — Biochemistry & Molecular Biology
Target concept: Enzymatic catalysis: Hydrogen peroxide is decomposed by catalase, resulting in foam formation.

Video generation prompt: Chop fresh potatoes and place them in a transparent glass beaker, alongside an identical empty beaker, then simultaneously add hydrogen peroxide to both beakers and observe the reaction.

Evaluation guide:
(i) Target concept: Enzymatic catalysis via biological catalyst (catalase) enabling rapid substrate decomposition under ambient conditions.
Minimum mechanism: Fresh potato tissue must contain active catalase; hydrogen peroxide must be chemically intact and unheated; reaction must proceed spontaneously upon contact without external energy input; oxygen gas evolution must be trapped in liquid matrix to form foam.
(ii)Storyline: [Phase 1: Setup] Two identical transparent beakers enter view, placed adjacent in fixed frontal frame; left beaker receives visibly chopped potato fragments (moist, off-white, irregular solids), right remains empty. [Phase 2: Intervention] Hydrogen peroxide (colorless liquid) is poured synchronously into both beakers; stream contacts potato surface and empty glass simultaneously. [Phase 3: Causal Response] Within visual continuity, foam emerges exclusively where liquid contacts potato; foam expands upward, remaining confined within left beaker; right beaker shows no surface agitation or gas release. [Perspective/Visibility Constraints] Frontal, eye-level viewpoint; full view of both beakers maintained at all times; no occlusion; lighting enables clear discrimination of foam vs. liquid vs. solid; potato texture and foam structure remain resolvable.

Manual:
Experimental Procedure
1. Place two identical transparent glass beakers side-by-side on a flat surface.
2. Chop fresh potato into irregular fragments and place them in the left beaker; leave the right beaker empty.
3. Simultaneously pour hydrogen peroxide into both beakers.
Observation of Experimental Phenomena
Foam forms rapidly and abundantly only in the beaker with fresh potato; no foam forms in the empty beaker.
Summary of Experimental Principles
Catalase enzyme in fresh potato tissue catalyzes decomposition of hydrogen peroxide into water and oxygen gas, causing visible foaming. The absence of catalyst in the empty beaker results in no observable reaction.

Prompt Grounding rubric:
level_1: No beaker holds any potato pieces and no hydrogen peroxide is shown being added to anything; only one beaker appears in the shot at all; the two beakers (one with potato, one empty) are never shown together in the same view; none of the setup steps described in the prompt (chopping the potato, placing it in one beaker, pouring peroxide into both) are shown happening.
level_2: One beaker is visible, but the second beaker (meant to stay empty) is missing, out of frame, or never shown together with the potato beaker in the same shot; the potato is absent, or looks whole or mashed rather than chopped; hydrogen peroxide is poured into only one of the two beakers, or the pour order contradicts the setup (for example the liquid is added before the potato is placed).
level_3: Two clear glass beakers appear together in the same shot; one holds visibly chopped fresh potato pieces, the other is empty; hydrogen peroxide is visibly poured into both beakers; all the key elements (the two beakers, the potato pieces, the peroxide liquid, and their placement next to each other) are present and correctly arranged.
level_4: Everything needed for a 3 is present, and beyond that: the potato pieces are clearly chopped into irregular chunks, not left whole or mashed into a paste; the two beakers match each other in shape, size, and clarity; the hydrogen peroxide reaches the contents of both beakers at essentially the same moment; no extra containers or tools appear in the shot that were not part of the setup.
level_5: Everything needed for a 4 is present, and beyond that: the potato pieces stay completely still and undisturbed until the peroxide reaches them; neither beaker moves relative to the other before or during the pour; the camera keeps both beakers in view the entire time, without either one becoming blocked or cropped out during the addition or the reaction that follows.

Scientific and Causal Correctness rubric:
level_1: No foam appears in either beaker; both beakers behave the same way as each other; there is no visible difference between the potato beaker and the empty beaker at any point; neither the liquid nor the potato pieces show any change of state.
level_2: Foam shows up, but not exclusively where it should: for example it appears in the empty beaker, or it appears in the potato beaker with no clear connection to when the peroxide was poured in; the liquid or the foam is an unexpected color, or the foam looks murky or opaque in a way real oxygen foam would not.
level_3: Foam builds up only in the beaker holding the chopped potato once the hydrogen peroxide reaches it; the empty beaker shows no foam at all; the foam is white and voluminous compared to how much liquid sits in the beaker; before the peroxide is added, the liquid in both beakers looks clear and colorless.
level_4: Everything needed for a 3 is present, and beyond that: the foam only starts appearing once the peroxide has actually touched the potato pieces, not before; the foam visibly rises higher than the liquid level inside the potato beaker; the empty beaker shows no bubbles, fizzing, or surface disturbance at any point in the clip.
level_5: Everything needed for a 4 is present, and beyond that: the foam keeps growing steadily for as long as the reaction is shown, without suddenly collapsing or stopping and restarting; the foam looks moist and cohesive rather than crumbly or grainy; there is no odd discoloration or debris sitting inside the foam layer.

Spatiotemporal Consistency rubric:
level_1: One of the two beakers disappears from view and reappears somewhere else on the bench without anything shown moving it; the chopped potato pieces vanish from their beaker and pop back in a different arrangement; the hydrogen peroxide appears to splash into the beakers with no visible stream or pour leading up to it; the whole scene swings from bright to dim lighting with no transition between one moment and the next; a beaker's rim visibly bends or warps out of its round shape.
level_2: The potato pieces shift to a different spot inside their beaker between frames without any liquid motion or stirring causing it; foam fills the potato beaker instantly in one frame with no build-up shown in the frames before it; the hydrogen peroxide stream looks like a frozen, rigid rod hanging in the air rather than a falling liquid; the shadow cast by the potato-filled beaker swings to face a clearly different direction than the shadow cast by the empty beaker, even though both sit under the same light.
level_3: Both beakers stay in the same spot on the bench with the same shape and size throughout; the hydrogen peroxide can be seen flowing continuously downward as it is poured into each beaker; the foam in the potato beaker grows step by step across the frames rather than jumping in size; neither beaker, the potato pieces, nor the foam flickers, warps, or briefly turns transparent; the empty beaker's glass and the potato beaker's foam are lit from the same single overhead light source in the first frame as in the last.
level_4: Everything needed for a 3 is present, and beyond that: neither beaker appears to shift sideways relative to the other, which would suggest the camera itself moved; the foam rises straight upward in the potato beaker rather than surging to one side or leaning; the liquid's surface in both beakers stays a single unbroken line as the hydrogen peroxide is added, without splitting or doubling; no frame freezes, repeats, or blends into the next in a way that looks like a skipped step.
level_5: Everything needed for a 4 is present, and beyond that: the falling hydrogen peroxide visibly speeds up and spreads out slightly as it drops, the way a real liquid stream would; the foam's surface shows small bubbles visibly joining into bigger ones as it expands, rather than looking like a static blob; there is no stutter, repeated frame, or blurred smearing inconsistent with how fast the foam is actually rising; the two beakers, the potato pieces, and the foam all stay in the same positions relative to each other and to the bench throughout, with nothing sliding out of place.