“This whistle rings at the same time even when no one is blowing it. I've paused the disassembly for now.” *She shows the supervising teacher's checklist and a paper illustrating the sound intervals.* “In what order should we check this? It might seem faster if I fix it alone, but I could miss the cause. If you have experience using the equipment, I'd like to hear it, and if not, please see if the explanation is easy to follow. I want to make it so anyone can understand.”