I am preparing a classroom exercise about what changes when an audio file is exported into different formats. I plan to use a short generated instrumental and keep its original export available to everyone. The first task would ask students to write listening notes before opening a visual display. I found mp3 to spectrogram as a possible reference while planning the visual part. We would then compare documented export settings using the same passage and a consistent playback level. The lesson needs to distinguish an observation in the image from a claim about its cause. A worksheet could separate audible observations, export settings, and questions that remain unresolved. The task would end with a comparison rather than a demand to fix the example. Students would record the software used for each export so that their comparison can be repeated later. Which comparison mistakes should I explain before students begin this exercise?