Lecture slides before or after? I am trying to work out if I should release slides for my lectures before or after the actual lectures. I don't think the projectors for the lectures are very good, and I think it would also be nice for students to follow along and also get an idea of the structure of the lecture with slides they can download. On the other hand I'm concerned that having these slides may promote disengagement. The slides are a somewhat cut-down version of the full lecture and won't contain all the details that the live version possesses: this might make the lecture a bit harder to follow along with downloaded slides... but on the other hand it will be clear what details are not going to be included in the downloadable version (so whether or not students need to take notes on such would be clear at the time).

The two approaches are mutually exclusive, so I'm struggling to work out which is the preferred option.
Students generally prefer to have the lecture slides beforehand, and you should let them make their own decisions about whether having the slides out during class will help their ability to concentrate.

On my first day teaching a class, I posted the lecture notes after the lecture, and I immediately got several requests along the lines of "can you post the lecture notes beforehand instead."

If you want engagement from the students, you should earn it by being a better lecturer.  Don't try to demand the students' attention by giving them fewer learning tools.