Slides should compliment the instruction, not replace it (and honestly, if one feels they DO replace it then they are probably not doing a very good job presenting it in the first place).
If the slides do not convey the material that is being taught, then the slides are useless. Students generally do refer to slides after lectures, and usually end up staring at a load of incomprehensible nonsense.
The instructor-expert can add flavour and understanding to the slides, and expound upon the points being made, but the slides should also stand alone as a resource.
A lecturer should appreciate that it's impossible to absorb a complex topic during a lecture, and provide resources that later complement what they are saying.
>If the slides do not convey the material that is being taught, then the slides are useless.
No. that's the point. Slides have one purpose only - to help the student during the talk. Attempting to make them dual-purpose, namely....
>Students generally do refer to slides after lectures,
Is to end up with the worst of both worlds. If the lecturer wants to distribute notes or a transcript after the lecture, that'a what they should do.
> but the slides should also stand alone as a resource.
Nope
A lecturer should appreciate that it's impossible to absorb a complex topic during a lecture, and provide resources that later complement what they are saying.
I agree with you on this point, but asking a lecturer to provide slides and notes creates a lot of work for them.
It's a difficult task to make one set to an adequate standard, so I was assuming you would use one set for both jobs (as seems to be the case in higher ed courses I'm familiar with).
I disagree that the slides have to be able to stand alone. Critical material shouldn't be completely ephemeral, but there's no reason that everything has to be on the slides. It can be in lecture notes, textbooks, and so on.