MediaViewer displays images with associated metadata on top of wiki pages. There is a dedicated dialog for downloading the images, but we suspect that many users use right click - save image instead (which is not good as this will save the thumbnail that was resized to match the size of their browser window, not the original image, which is probably what they wanted).

To find out exactly how many, log right clicks on the images displayed by MediaViewer. An example patch for logging a new event is https://gerrit.wikimedia.org/r/#/c/175622. The EventLogging schema used by MediaViewer is Schema:MediaViewer. (You can find a description of EventLogging here, although it's a bit more detailed than would be ideal. But using the example patch and the page history it's pretty easy to figure out what to do.)

This is T75962 in Wikimedia's issue tracker.

Students are required to read Wikimedia's general instructions first.