In the scene, the upper structure has a missing piece outlined with a dashed line. There are 4 candidate pieces below. The video sequentially checks each candidate from left to right: highlights the current candidate being examined with a frame, previews how the piece fits in the gap, then judges it: if the shape matches, its box turns green and is marked with a green ✓; if it doesn't match, its box turns red and is marked with a red ✗. It then moves to the next candidate. Once the matching piece is found, an animation demonstrates it moving into the gap to complete the structure. Only modify what the task requires; keep the background and any other element unchanged.