Domain: Natural Science — Physics
Target concept: Spring in Series

Video generation prompt: Two sets of spring scales are vertically suspended side by side on the wall, with one end fixed. The left set consists of a single spring scale, while the right set comprises two spring scales of the same type as the left one, connected in series end to end. A metal weight of 500 g is suspended from the left spring scale, and a metal weight of 500 g is also suspended from the right spring scale.

Evaluation guide:
(i) Target concept: Hooke's Law applied to two springs connected in series: because tension is transmitted unchanged through an ideal massless spring, each spring in the right-hand series pair carries the same 500 g load as the single left spring, so each individual spring (left, right-upper, right-lower) stretches by the same amount; the two right-hand extensions add together, making the right side's total length increase about twice the left spring's.
Minimum mechanism: Springs must behave linearly (F = kx) and be effectively massless; the hook-to-ring joint between the two right-hand springs must transmit force fully with no slippage or bending; each weight must come to rest so a stable, static extension can be observed.
(ii)Storyline: Frame 1–2: Static wide shot shows the wall-mounted side-by-side setup (left: one spring scale; right: two spring scales chained vertically). Frame 3–4: The two 500 g weights are attached: the left weight lands on the left scale's lower hook; the right weight lands on the lower hook of the bottom spring on the right. Frame 5–8: All three springs stretch and settle; the left spring reaches a stable elongation; the right-hand upper and lower springs each reach a stable elongation that looks about the same as the left spring's (since each also carries a 500 g load), so the two right-hand springs' combined length increase looks roughly double the left spring's. Frame 9–10: The system holds still (no bouncing, no further sagging, no hook slipping loose), confirming static equilibrium. Viewpoint: Fixed frontal angle keeping every hook, coil, and weight visible without anything blocking the view.

Manual:
Experimental Procedure
1. Mount two identical spring scales side-by-side on a vertical wall: left uses one scale; right connects two identical scales end-to-end in series.
2. Suspend a 500 g metal weight from the lower hook of the left spring scale.
3. Suspend a 500 g metal weight from the lower hook of the bottom spring scale in the right series.
Observation of Experimental Phenomena
The left spring scale extends visibly. In the right-hand series, both the upper and lower spring scales extend visibly, and each extends by an amount that looks about the same as the left spring's extension; together, their combined length increase looks roughly twice that of the left spring.
Summary of Experimental Principles
In a series configuration, the same force (the 500 g weight) acts on each spring in the chain, and total extension equals the sum of the individual extensions. Since the springs are identical (same spring constant k) and each carries the full load, each spring stretches by the same amount, so total extension of the right side = 2× the extension of the left side. (Note: this assumes ideal massless springs and static equilibrium.)

Prompt Grounding rubric:
level_1: No wall-mounted spring scales are visible at all; the left and right assemblies are not shown together in the same shot (e.g., one is stacked above the other, shown in a separate shot, or overlapping the other); neither the left weight nor the right weight is visible hanging from anything.
level_2: A wall and at least a hint of spring-scale hardware appear, but the setup is clearly wrong: only one side (left or right) is present in the scene; a 500 g weight rests on a table or floor instead of hanging from a hook; the right side shows only a single spring scale rather than two joined in series; or the left and right assemblies are never shown mounted on the same wall at the same time.
level_3: Both assemblies appear on the same wall at the same time: the left side is one spring scale with a 500 g metal weight hanging from its lower hook; the right side is two spring scales of the same type joined end-to-end (the upper scale fixed to the wall, the lower scale hanging from the upper scale's lower hook, and a 500 g weight hanging from the lower scale's lower hook), matching the posted setup.
level_4: Everything in the 3-point level holds, and in addition: the two spring scales on the right are visibly the same model as the one on the left (same housing shape, same dial markings, same hook style); the two weights look like matching metal cylinders or blocks of the same color and finish; nothing blocks the view of either assembly; the camera holds one fixed, frontal framing showing both assemblies from top to bottom.
level_5: Everything in the 4-point level holds, and in addition: the join between the two right-hand spring scales is clearly readable: the lower hook of the top scale sits inside the upper ring of the bottom scale with no visible gap; both weights are shown fully attached to their hooks with nothing floating loose or disconnected; neither assembly shows a visual glitch such as a see-through or flickering spring housing, or a shadow that doesn't match the object casting it; both assemblies stay fully on screen for the whole clip with no cut, pan, or zoom.

Scientific and Causal Correctness rubric:
level_1: The video contradicts basic spring mechanics: the right-hand series pair (two springs under the same 500 g load) shows less total stretch than the single left spring; neither side shows any stretch at all despite a weight hanging; a spring stretches with no weight attached; or a spring keeps stretching indefinitely and never settles.
level_2: The extension pattern breaks series-connection logic: only one of the two right-hand springs stretches while the other stays at its unloaded length; the left spring shows no visible stretch even though its weight is hanging; or the visible deformation shows up somewhere other than the coils (such as a bent hook) instead of in the spring body itself.
level_3: The left spring's coils visibly stretch beyond their unloaded length once its weight is hanging; the top spring on the right visibly stretches; the bottom spring on the right also visibly stretches; all three stretching events happen together, at essentially the same time as each weight is attached, with no noticeable lag between the two right-hand springs.
level_4: Everything in the 3-point level holds, and in addition: the two right-hand springs (top and bottom) stretch by visibly similar amounts to each other and to the left spring. Since every spring here carries the identical 500 g load, no single spring should look like it stretched noticeably more or less than any other single spring. The combined length added by the two right-hand springs together looks roughly twice the single left spring's added length, while no individual right-hand spring looks shorter or longer in its own stretch than the left spring.
level_5: Everything in the 4-point level holds, and in addition: all visible stretching is confined to the coiled bodies of the springs: the wall bracket, the hooks, and the weights themselves do not deform; the coil spacing on each stretched spring opens up evenly along its length with no kinks or localized bunching; once each weight settles, all three springs stop changing length at the same time, with no lingering bounce or creep on either side.

Spatiotemporal Consistency rubric:
level_1: A major break in continuity: a spring scale or a weight vanishes from view and reappears in a different spot; the camera cuts abruptly between a wide shot and a close-up; the wall, a hook, or a weight jumps to a new position between frames with no motion shown in between; a spring housing visibly splits or breaks apart with no mechanical cause.
level_2: A noticeable but less severe break: a spring scale blinks out of view for part of the clip and then reappears in the same place; a weight swings more than 30° from vertical and then stops abruptly with no transition; the shadow beneath a weight detaches from the weight as it moves; the gap between the two right-hand spring scales opens or closes with no matching stretch or relax of the coils.
level_3: Both assemblies stay in place and intact for the whole clip: the left spring scale stays vertical and does not shift sideways; the two right-hand spring scales stay connected and vertical as a chain; both weights stay attached to their hooks throughout; nothing on either side blinks out, reappears, or suddenly changes size; the wall lighting stays even, without the shadows swinging to a different angle or brightening and dimming abruptly.
level_4: Everything in the 3-point level holds, and in addition: any motion looks physically reasonable: for example, a brief settling wobble right after each weight is hung, dying out at a similar rate on both sides; a weight never appears to pass through the coils of its own spring; no spring housing bends or squashes out of shape.
level_5: Everything in the 4-point level holds, and in addition: no frame is blurred enough to hide the coils or the hook-to-ring connection; the camera itself looks steady, with the wall and both spring assemblies moving together as one (no background sliding relative to the foreground that would suggest camera shake); the side-by-side layout, the vertical alignment, and the series connection on the right all look stable and unchanged by eye from the first frame to the last.