Domain: Engineering — Aerospace Engineering
Target concept: The airfoil generates lift due to the Bernoulli effect, with slight upward vibration or displacement, but no significant rotation or rolling.

Video generation prompt: A wing section made of thin paper is fixed as a cantilever in front of a desktop fan; the fan is turned on to produce a steady airflow over the wing section.

Evaluation guide:
(i) Target concept: Steady-state aerodynamic lift on a fixed cantilevered airfoil section in uniform axial flow.
Minimum mechanism: Air flows roughly parallel to the paper strip's length, fast enough to create a visible pressure difference between its two faces; the strip is clamped at the root (no rotation there) but free to deflect at the tip; the paper is thin and pliant enough to develop a slight upward camber under this pressure difference while staying intact (no tearing, no flapping apart); this camber is what lets air move faster over the upper surface, producing the lift described below.
(ii)Storyline: [Frame 0–2] Static setup: strip clamped at its root, fan off, strip horizontal and still. [Frame 3–4] Fan activation: blades begin turning, airflow starts (visible via nearby streamers if present). [Frame 5–8] Causal response: the strip's tip rises toward an elevated position, developing a gentle upward camber, with at most slight vibration around the rising trend; no rotation or lateral drift. [Frame 9–10] Sustained state: the tip holds its elevated position (small vibration is normal) while the fan keeps running; the entire sequence is viewed from a fixed frontal/slightly oblique angle showing both the strip's length and the fan face-on; the strip's tip and clamp region stay unobstructed throughout.

Manual:
Experimental Procedure
1. Fix one end of a thin rectangular paper strip (airfoil cross-section) horizontally to a rigid base using a clip or clamp — forming a cantilever.
2. Position a desktop fan directly upstream, aligned with the paper's leading edge.
3. Turn on fan to generate steady airflow over the upper and lower surfaces.
Observation of Experimental Phenomena
The paper strip's free tip rises toward an elevated position, developing a slight upward camber as air passes over it; small vibration around this raised position is normal, but the strip does not roll, spin, or drift sideways.
Summary of Experimental Principles
Lift arises because the strip's slight upward camber lets air move faster over its upper surface than its lower surface, creating a pressure differential (Bernoulli effect); the resulting net upward force raises the cantilevered tip, with only slight vibration and no significant rotation or rolling.

Prompt Grounding rubric:
level_1: No paper strip is visible anywhere in the scene, no desktop fan appears, and no clamp or base holding a strip is shown; none of these three required elements (paper strip, fan, clamp) can be identified in the frame.
level_2: Only one of the three required elements is visible (for example, a fan with no paper strip anywhere, or a loose paper strip with no fan in frame); or a strip and a fan both appear but never share the same shot, or the strip is not attached to any base or clamp.
level_3: The paper strip, a desktop fan, and a clamp/base holding one end of the strip all appear together in a single continuous shot; the fan is switched on (blades turning or nearby streamers moving); the clamp holds the strip near one end (its root), leaving the rest of the strip free and unsupported.
level_4: Everything described for level 3 is present. The strip's free end also points toward the fan (the fan's airflow axis lines up with the strip's length rather than hitting it from the side or above), the clamped root shows no visible gap or looseness, and nothing in the scene blocks the view between the fan and the strip.
level_5: All of level 4 continues to hold. The paper strip additionally stays in one intact piece for the whole clip (no tearing, crumpling, or fraying), the fan's blades keep turning at a steady rate without stalling or restarting, and the clamp/base never slips or shifts from where it was mounted: the physical rig (fixture, fan, strip) remains stable throughout, independent of how the strip's tip moves in response to the airflow.

Scientific and Causal Correctness rubric:
level_1: The strip's free tip does not rise once the fan is on: it stays put, sags downward, or the whole strip rotates, rolls, or flips end-over-end; or the tip is pushed backward/downstream instead of lifting; the airflow appears to have no lifting effect at all.
level_2: The tip shows a rise mixed with a large rotation, twist, or sideways swing of the strip, so the dominant visible motion is not a clean upward rise; or the tip briefly rises then drops back well below its starting height and stays down while the fan keeps running.
level_3: After the fan starts, the strip's free tip rises above its resting height and settles near an elevated position while the fan runs; the strip does not roll, spin, or flip; any wobble present is minor and does not reverse the overall upward trend.
level_4: Building on level 3, the tip's path is mostly straight upward with no visible sideways drift toward either edge of frame, the strip keeps roughly the same twist/tilt it started with (no rotation building up over the clip), and the rise begins within roughly the first half of the clip rather than after a long unexplained delay.
level_5: Building on level 4, the tip settles into a steady elevated height while the fan keeps blowing; small vibration or flutter around that height is expected and acceptable, but there is no large rebound back to the starting height and no runaway flapping; the strip's upper surface shows a gentle continuous curve (consistent with airflow-induced camber) rather than staying perfectly flat, and the paper shows no tearing or creasing.

Spatiotemporal Consistency rubric:
level_1: The clip contains a hard cut, freeze-frame, or time jump; or the paper strip or fan abruptly appears in a new position with no motion shown getting it there; or the strip appears to pass through the clamp or fan, or turns see-through where it should be solid paper; or the lighting on the scene abruptly shifts brighter or darker (or shadows invert direction) with no physical cause.
level_2: The strip's motion shows a jarring skip or repeat, or the fan blades' spin direction reverses without explanation, or the clamp/base appears to shift relative to the desk between shots, or a hand or object appears/disappears near the clamp with no visible cause, or the shadow cast by the strip or fan shifts direction between frames without a matching change in the light source.
level_3: The strip, fan, and clamp keep consistent positions and sizes relative to each other across the clip; the strip's rise (and any camber it develops) unfolds as continuous motion with no skipped frames or stutters; the fan keeps spinning without direction reversal; the lighting and shadow direction stay consistent with a single, unmoving light source throughout; no part of the setup flickers, vanishes, or swaps shape.
level_4: In addition to level 3, the camera viewpoint stays fixed with no pan, tilt, or zoom; the desk and clamp base show no sliding or drifting relative to each other; the strip's edges stay recognizable (not smeared into an unrecognizable blur) as it rises; the fan blades show natural spinning motion rather than an unnaturally frozen or strobing look.
level_5: In addition to level 4, the strip's rise reads as one smooth, connected motion from start to end with no visible skips or freezes; the fan stays behind the strip and the clamp stays in front of it in a way that looks physically consistent throughout (no part of the rig appears to swap depth order); any glare or reflection from the fan on the paper appears only when the strip is angled toward it, not at random moments.