It does vary from module to module but unless the module is about, say, resolution - as in the last module or sharpening then a good guide would be a 1000 pixel image height saved as a maximum quality jpeg. From that a tutor could easily see if you had correctly adjusted levels, righted a wonky image or used the correct white balance setting. All that without crashing their computer or filling up your pen drive with a single image(yes that has happened!)

Garry