Domain: Humanities and Social Sciences — Sport
Target concept: Front Crawl Flip Turn Demonstration

Video generation prompt: The athlete swims freestyle toward the wall, lowers the head, pulls the knees in for a forward flip turn, pushes off the wall, and adjusts the posture before continuing to swim forward.

Evaluation guide:
(i) Target concept: A biomechanically valid forward somersault turn in freestyle swimming, governed by conservation of angular momentum and force application against a rigid boundary.
Minimum mechanism: Swimmer must be in forward translational motion pre-turn; head lowering must precede and trigger rotational initiation; tuck must reduce moment of inertia to accelerate rotation; wall contact must occur during peak forward rotation; push-off must apply force perpendicular to wall surface to generate linear acceleration along swimming axis.
(ii)Storyline: Phase 1 (Approach): Swimmer fully visible, arms stroking, body horizontal, moving straight toward wall. Phase 2 (Initiation): Head visibly dips below water surface while arms recover forward; knees begin drawing upward. Phase 3 (Rotation): Torso curls forward, hips flex, feet rise toward wall; rotation center remains near navel; no lateral drift. Phase 4 (Contact & Propulsion): Both feet land flat on wall simultaneously, shoulder-width apart; legs extend fully; body launches forward. Phase 5 (Recovery): Body elongates into tight streamline (arms extended overhead, head between arms, back flat); begins forward glide. Perspective constraint: Fixed frontal or oblique underwater view capturing full body and wall; no aerial or overhead angles that obscure foot-wall contact or rotation axis. Visibility constraint: All critical joints (head, shoulders, hips, knees, ankles) remain discernible throughout; water clarity sufficient to distinguish limb positioning and wall contact.

Manual:
Experimental Procedure
1. Swimmer approaches pool wall in continuous freestyle stroke.
2. At ~1m from wall, swimmer lowers head and initiates forward rotation by pulling knees tightly to chest.
3. Swimmer completes forward somersault, contacts wall with both feet shoulder-width apart.
4. Swimmer pushes forcefully off wall with extended legs into streamlined position.
5. Swimmer adjusts body alignment underwater to resume forward freestyle swimming.
Observation of Experimental Phenomena
- Head lowers before knees tuck.
- Knees pull in symmetrically and compactly.
- Forward rotation is continuous and centered around mid-torso.
- Feet contact wall simultaneously and flatly.
- Push-off produces immediate horizontal propulsion.
- Body transitions from curled → extended → streamlined orientation.
Summary of Experimental Principles
Front crawl flip turn requires coordinated timing: head-down entry reduces drag and initiates rotation; tight tuck maximizes angular velocity; wall contact with flexed hips/knees stores elastic energy; leg extension converts stored energy into forward thrust; streamline posture minimizes resistance for breakout.

Prompt Grounding rubric:
level_1: No swimmer is visible, the swimmer is doing a stroke other than freestyle, the pool wall never appears in frame, or the swimmer never attempts any kind of turning motion at the wall.
level_2: A swimmer freestyles into frame, but the wall is never shown during the approach, the head stays up rather than dipping down, or the knees never visibly draw in toward the chest before reaching the wall.
level_3: The swimmer freestyles toward the wall, the head visibly lowers, and the knees draw in (in that order), but the push-off from the wall is missing or incomplete (no visible leg extension), or there is no visible adjustment of body position after leaving the wall.
level_4: All five expected actions appear in the prompt's order (freestyle approach, head lowering, knee tuck, wall push-off with leg extension, and a body-alignment adjustment into forward swimming), but one small, non-disruptive flaw is present, such as the swimmer briefly leaving the frame, the foot-to-wall contact being partly hidden by splash, or the arm position during the flip looking slightly different from a textbook turn without breaking the visible sequence.
level_5: All five actions appear in the prompt's order with the swimmer fully visible throughout: the wall is clearly present and contacted, the head visibly lowers before the knees tuck, the somersault rotation reads as one smooth continuous motion, the legs visibly extend against the wall, and the swimmer smoothly transitions into a straight, streamlined swimming posture afterward, with no part of the body hidden, no jump cut, and no confusing or out-of-order motion.

Scientific and Causal Correctness rubric:
level_1: The turn shows no cause-and-effect at all: the swimmer stops dead at the wall without ever curling into the flip, begins tucking and rotating without the head ever dipping down first, rotates while still far from the wall with no contact ever occurring, or pushes off the wall while the body is still straight and extended rather than having tucked and rotated first.
level_2: The head dips down and the body curls into the tuck, but tucking tighter does not visibly speed up the rotation (the somersault turns at the same lazy rate whether tucked or open); or the knees tuck and the body begins rotating before the head visibly dips down; or the feet touch the wall but the legs never visibly extend, so no push results from the contact; or after leaving the wall the body stays curled or vertical instead of stretching out to move away from the wall.
level_3: The head visibly dips down before the knees draw in, the rotation visibly speeds up once the knees draw in tightly toward the chest (the somersault clearly turns faster during the tucked phase than during the open, extended phase right before it), and the legs are seen extending against the wall right as the swimmer moves away from it, but one of these links looks weak or ambiguous, such as the head-dip-to-tuck timing being hard to tell apart, the speed-up during the tuck being hard to see clearly, or the leg extension only partly overlapping with the visible movement away from the wall.
level_4: All causal links from the 3-point description are clearly visible: the head dipping down visibly precedes and triggers the knee tuck, the tighter the knees draw in the faster the body visibly spins, and the legs' extension against the wall visibly and directly produces the swimmer's motion away from the wall, with at most one small, non-disruptive imperfection, such as a brief moment where the rotation speed is a little hard to judge because of splash, without breaking the visible cause-and-effect.
level_5: The head-down motion unmistakably precedes and triggers the tuck, and the link between tucking and spin rate is unmistakable throughout (the body visibly spins fastest exactly when the knees are drawn in tightest and visibly slows again as the body stretches back out afterward), and the leg extension against the wall visibly drives the swimmer directly forward with no visible stall, backward drift, or sinking; every step in the chain, from approach through head-down, tuck-triggered speed-up, wall contact, push-off-driven forward motion, to streamline, reads as one continuous cause producing the next effect.

Spatiotemporal Consistency rubric:
level_1: The swimmer's body suddenly appears in a different spot in the pool with no visible motion connecting the two positions, the wall vanishes and reappears, the overall brightness of the water swings sharply lighter or darker partway through the turn with no visible cause, a limb blinks out of view and reappears elsewhere, the motion freezes completely and then jumps ahead, or the camera suddenly cuts to a different angle or shot instead of holding the single continuous underwater view of the turn.
level_2: The swimmer stays hidden behind the lane line or the wall's edge for longer than a moment, the water's surface level shifts inconsistently between frames, a kicking leg vanishes mid-kick and reappears in a different position, or the head jumps from above the surface to fully underwater with no in-between motion visible.
level_3: One clear break in the flow stands out: for example, the frame right before wall contact shows the feet not yet touching the wall but the very next frame already shows a full push-off with legs extended, or the somersault rotation looks choppy with a missing middle portion, or the torso's facing direction changes with no visible turning motion shown in between.
level_4: The swimmer's path toward the wall, the tuck into rotation, the wall contact and push-off, and the following body-alignment all flow as one unbroken sequence of motion, with at most one small, brief hiccup, such as a splash covering the feet for a moment or a slight stutter in a limb's motion that does not break the overall flow.
level_5: The swimmer's entire body stays visible and the motion never breaks: the rotation of the head, hips, and knees advances step by step with nothing skipped, the wall stays fixed and steady in the frame, the splash and water movement change naturally in step with each phase of the turn, and no part of the image flickers, jitters, or looks warped or blurred out of shape at any point.