Animate the classroom apparatus in Image 1 as a qualitative wave demonstration. Preserve the rectangular tank, fixed divider with one narrow gap, blue paddle on the near side and red cork beyond the gap. The opening water surface is still.

0–3s: the paddle makes one small forward displacement, creating a low-amplitude surface disturbance. 3–8s: show the disturbance traveling toward the barrier, passing through the gap and spreading on the far side. 8–12s: the cork bobs gently as the disturbance reaches it; keep its average position nearly unchanged.

Use a locked high three-quarter camera, readable reflected light and a faint water sound. No exaggerated splashes, water crossing solid barrier sections, cork racing with the wave, measurement labels or numerical claims. Generated motion is an illustration, not a scientific simulation or observed experiment; reject incorrect propagation.