Domain: Natural Science — Statistics & Data Science
Target concept: Negatively correlated features: The points in the scatter plot are regularly distributed from the upper left to the lower right.

Video generation prompt: Prepare a set of paired variables with negatively correlated characteristics, and plot them as a scatter plot to reveal a clear trend. The procedure should remain simple and orderly, with the focus on highlighting the emerging trend in the scatter plot.

Evaluation guide:
(i) Target concept: Visual emergence of monotonic inverse association between two quantitative variables via Cartesian scatter plot.
Minimum mechanism: Two measurable variables must be defined such that higher values of one correspond systematically to lower values of the other; Cartesian coordinate system must be intact (x rightward, y upward); point placement must respect ordinal consistency across both dimensions.
(ii)Storyline: Frame 1–2: Clean blank canvas → axes fade in simultaneously with correct orientation and labeled axes. Frame 3–5: Data points appear sequentially or collectively, each positioned strictly so that increasing x-coordinate corresponds to decreasing y-coordinate relative to prior points. Frame 6–10: Full plot remains static, fully visible, with no motion, distortion, or occlusion; viewer perspective is fixed frontal orthographic (no rotation, zoom, or parallax); all elements remain within safe margins and retain legibility.

Manual:
Experimental Procedure
1. Display labeled x- and y-axes on screen.
2. Plot ≥5 data points that decrease together: as x-value increases, y-value decreases.
3. Ensure points form a clear upper-left to lower-right pattern.
Observation of Experimental Phenomena
A scatter plot appears with points regularly aligned from top-left toward bottom-right — no randomness, no reversal, no clustering away from the diagonal descent.
Summary of Experimental Principles
Negatively correlated features: The points in the scatter plot are regularly distributed from the upper left to the lower right.

Prompt Grounding rubric:
level_1: No scatter plot is present; no coordinate axes are visible; no data points are shown.
level_2: A plot appears but is missing a labeled x-axis, a labeled y-axis, or any data points; or the chart is not a scatter plot at all (e.g., a bar chart, a line chart, or a single-axis histogram).
level_3: A scatter plot is present with a visible, correctly oriented x-axis (increasing rightward) and y-axis (increasing upward), and at least 5 distinguishable data points are plotted; axis labels are absent, illegible, or generic/unnamed (e.g., just 'X' and 'Y' with no stated meaning).
level_4: The scatter plot has clearly labeled x- and y-axes with readable variable names, at least 5 distinguishable data points, and correctly oriented axes; every point renders as a distinct, non-overlapping marker.
level_5: The scatter plot has clearly labeled x- and y-axes naming two real, measurable quantities (for example 'temperature' and 'gas solubility,' 'altitude' and 'atmospheric pressure,' or 'car age' and 'resale value') rather than placeholder or nonsensical labels; at least 5 distinct markers are plotted on correctly oriented axes, and every element (axes, labels, points) stays fully visible and legible in frame.

Scientific and Causal Correctness rubric:
level_1: The plot shows no trend at all, or plainly contradicts a negative correlation: for example the points form an upward-sloping cluster, a uniform grid with no slope, or a diagonal band with a positive slope.
level_2: Axes and at least 5 points are present, but the trend direction cannot be determined: the points form a horizontal or vertical band, are too scattered to show any gradient, or all sit in the same row or column.
level_3: The points show a rough upper-left-to-lower-right tendency, but the pattern breaks from a clean negative correlation in more than one place: for example the points curve into a U-shape or an S-shape, or two or more points sit far off the main descending band in a way that disrupts the overall downward direction.
level_4: The points trace a clear upper-left-to-lower-right descending trend with no segment that reverses into a rising slope; at most one point sits noticeably off the main trend as a mild outlier; the axes are conventionally oriented (x increasing rightward, y increasing upward), so the visual descent genuinely reflects a negative relationship rather than an artifact of a flipped axis.
level_5: Every point is consistent with a single, unbroken downward trend from upper-left to lower-right: as x increases, y never increases from one point to the next along the trend; the axes are conventionally oriented; the two labeled variables form a real-world pair that is genuinely negatively correlated (e.g., 'temperature' and 'gas solubility,' 'speed' and 'travel time over a fixed distance,' or 'altitude' and 'atmospheric pressure'); no artifact (overplotting, a forced straight-line fit, or artificial clustering) misrepresents the strength of the negative correlation.

Spatiotemporal Consistency rubric:
level_1: The whole plot appears or disappears abruptly mid-video; the axes redraw themselves partway through; points jump to new positions between one frame and the next; a large flicker or dropped section blocks more than a third of the video where the plot should be visible.
level_2: An axis visibly shifts position or orientation between frames; two or more points blink on or off abruptly instead of appearing smoothly; the grid lines bend or shear at some point; the background color or brightness changes suddenly while the plot is on screen.
level_3: One axis label fades in noticeably later than the data points; one point's entrance looks inconsistent with the others (for example it slides in while the rest pop into place at once); one label flickers briefly, or the points show a small amount of visible wobble in place rather than staying still.
level_4: The axes, labels, grid lines, and every point stay in the same place throughout the video; nothing moves, warps, or gets redrawn after it first appears; any reveal animation, such as points appearing one at a time, plays at a consistent pace and from a consistent starting direction; lighting stays even; no axis or label is cut off or clipped by the frame edge.
level_5: The axes, labels, grid, and every point stay perfectly still and identically drawn in every single frame; any point-by-point reveal animation uses the same timing and motion style for every point; there is no visible flicker and no jagged edges appearing or disappearing between frames; the complete plot stays fully visible and geometrically unchanged from the first frame to the last.