I am quite new to LaTeX so my question may be trivial, but I haven't found a good solution so far.

I am preparing some lecture notes and I would like to have 2 different versions: one for myself, containing all the info I need during the lecture, and one for the students, with some of the text and/or graphics and/or equations blanked out (with some white space occupying the same space on the page, so the students could fill the gaps). I know of `\phantom`,
but it does not seem very efficient as I would have to prepare 2 versions of the same document. I have also seen the `censor` package, but it does not seem to play nicely with equations. Any other suggestion on how to do this cleanly and efficiently?