Domain: Engineering — Computer Science
Target concept: Demonstration of the Bubble Sort Algorithm Execution Process

Video generation prompt: Display a simple horizontal array of numbered bars on a clean white background (e.g., [3, 4, 1, 2]). Animate the process of sorting the array into ascending order using the Bubble Sort algorithm step by step.

Evaluation guide:
(i) Target concept: Algorithmic state evolution via pairwise comparison and conditional exchange in a deterministic iterative process.
Minimum mechanism: Bars must represent immutable data elements; adjacency must be spatially encoded as immediate left-right neighbor relationship; comparison must temporally precede and causally trigger swap; final sorted order must emerge solely from repeated local decisions.
(ii)Storyline: Frame 0–1: Initial state, four numbered bars [3,4,1,2] horizontally aligned on white background, all unhighlighted. Frame 2–3: First comparison, bars 3 and 4 highlighted; no motion. Frame 4–6: Second comparison, bars 4 and 1 highlighted; then bars 4 and 1 smoothly exchange positions. Frame 7–9: Third comparison, bars 4 and 2 highlighted; then bars 4 and 2 smoothly exchange. Subsequent passes continue identically until convergence. Perspective: Fixed frontal orthographic view; no camera movement; all bars fully visible and non-occluded at all times.

Manual:
Experimental Procedure
1. Display horizontal array of 4 rectangular bars on clean white background, labeled top-center with numbers [3, 4, 1, 2].
2. Highlight first two bars (3 and 4), compare: since 3<4, no swap.
3. Highlight next two bars (4 and 1), compare: since 4>1, swap positions smoothly.
4. Highlight next two bars (4 and 2), compare: since 4>2, swap positions smoothly.
5. Repeat passes until array becomes [1, 2, 3, 4], with final state stable for ≥1 second.
Observation of Experimental Phenomena
- Bars move only horizontally during swaps, never vertically or diagonally.
- Exactly two adjacent bars are highlighted before each comparison.
- After each swap, bar numbers remain intact and legible in new positions.
- Final array is strictly ascending left-to-right: [1, 2, 3, 4].
Summary of Experimental Principles
Bubble Sort repeatedly steps through the list, compares adjacent items, and swaps them if they are in wrong order. Each pass places the next-largest element in its correct final position.

Prompt Grounding rubric:
level_1: No horizontal array of bars appears; the background is not a plain white; there is no animation at all, or the bars never move; nothing resembling a sort visualization is shown.
level_2: A row of bars is shown, but they lack numbers or use the wrong shape (e.g., circles or text-only labels instead of bars); the background is not plain white; no comparison or swap motion ever occurs.
level_3: Four numbered bars matching [3, 4, 1, 2] appear in a row on a plain white background; some animation begins, with at least two different pairs of adjacent bars highlighted at some point, but the clip stops or stalls before the array reaches ascending order [1, 2, 3, 4].
level_4: All four required bars appear in a row on a clean white background, each showing its correct starting number (3, 4, 1, 2) clearly and legibly; the animation runs through a sequence of adjacent-bar highlights and swaps and ends with the bars in ascending order [1, 2, 3, 4]; no extra shapes, text, or UI elements clutter the frame.
level_5: All of score 4, AND every highlighted pair is shown clearly before its bars move, with the swap itself gliding smoothly to the new position with no overlap or momentary hiding of either bar; bar numbers stay sharp and readable in every frame, including mid-swap; no frame shows a bar with the wrong number, a duplicate number, or bars sitting at mismatched heights.

Scientific and Causal Correctness rubric:
level_1: Bars change places without any adjacent pair ever being highlighted first; the array never ends up in ascending order; the numbers shown do not match the starting values 3, 4, 1, 2 or the final values 1, 2, 3, 4; a swap happens with no highlighted comparison shown before it.
level_2: Swaps happen between bars that are not next to each other; a bar jumps straight to a new spot instead of sliding past its neighbor; the final order is descending or otherwise not 1, 2, 3, 4; at least one bar shows an incorrect number at some point (e.g., a 3 turning into a 5, or a missing digit).
level_3: Every bar keeps its correct number throughout; all swaps happen strictly between neighboring bars; the array ends ascending as [1, 2, 3, 4]; however, at least one required comparison from the true bubble-sort trace is skipped (for example the (4,1) pair is never highlighted before they swap), or one swap happens out of the correct order for that pass (e.g., 4 swaps with 2 before it has been compared with 1).
level_4: All of score 3, AND bar numbers only ever change position via an explicit swap, never silently; every swap is immediately preceded by a highlight of that exact adjacent pair; the array reaches ascending order [1, 2, 3, 4] and no further swaps happen once it does; every intermediate arrangement shown is a valid step along the true bubble-sort path for [3, 4, 1, 2].
level_5: All of score 4, AND the trace matches bubble sort exactly: pass one compares (3,4) with no swap, then (4,1) with a swap, then (4,2) with a swap, leaving [3,1,2,4]; pass two compares (3,1) with a swap, then (3,2) with a swap, leaving [1,2,3,4]; pass three compares (1,2) with no swap, confirming the array is sorted; no comparison or swap happens after this point; bars change only in position through swaps and in highlight color during comparison, never in height, width, or identity.

Spatiotemporal Consistency rubric:
level_1: A bar disappears and reappears, or suddenly changes size or position with no motion shown in between; the white background changes color or texture partway through; two bars sit in the exact same horizontal spot at the same time; a bar tilts or rotates instead of just sliding left-right.
level_2: Bars stay level and in a row, but a swap looks jerky: a bar sits frozen for a couple of frames, then suddenly jumps to its new spot; two bars visibly overlap mid-swap; a highlight pops on or off instantly with no fade; the white background shows visible blockiness or an uneven gradient instead of a flat white.
level_3: Bars only ever move sideways, and only during a swap, sliding continuously from their old spot to their new one with no overlap along the way; the background stays a flat, even white with no shift in lighting; exactly two neighboring bars are highlighted at a time, and the highlight stays on until their swap finishes.
level_4: All of score 3, AND every swap's motion is smooth from start to finish with no stutter, freeze, or sudden speed-up; the gaps between bars stay the same width before, during, and after each swap; the highlight color and shape look the same every time it is used; no bar looks stretched, skewed, or resized as if the camera's perspective had shifted.
level_5: All of score 4, AND every bar keeps the same height and width and sits on the same baseline for the entire clip; the spacing between bars never varies from one moment to the next; the highlight never spills past a bar's edges; no bar shows a motion trail or streak that does not match how fast it is actually sliding; the camera's framing never pans, zooms, or tilts at any point.