There is a class in Canvas that can be added making elements visibile screenreaders only. You simply add <span class="screenreader-only">instruction only for screenreaders< /span> and it is done. This is very handy and can be used to create a more accessible content for students using screen readers.
The problem, as we recently discovered the hard way, is that a teacher will not be able to see which content will be "hidden" on the published page and what will be visible, in the editor it all looks the same. So we had a teacher who created a page and set it to be published days later, and only when students got in touch being unable to see some links did we learn about this option.
So to avoid future problems we would like to suggest that elements with this class should be highlighted in the editor in order to avoid confusion.