... or you can use Libre Office or a recent version of MS Word and save directly as a PDF, or install a PDF printer (such as pdf creator) and access via File, Print. There are lots of simple ways of creating PDFs these days, but it still doesn't prevent the extra step(s) involved being an issue to some students (and using zamzar.com, simple though it is, would appear to be one of the more complex options available). Automatic conversion on the server would be the ideal.