Citations needed when using textbooks to write lecture notes/slides? so basically I have recently started to teach my own course for the first time. In the past, I mainly taught professors in the department that were on leave etc and they normally supplied me with their teaching materials, so this is the first time I am completely writing my own notes/lecture slides.

Now, I am teaching a history survey course and when writing lecture notes/slides, I have mainly relied on the course textbook and a few secondary sources. The question now is whether I need to provide references at all if I use the work of others in this context? I do not copy anything verbatim of course and also dont claim anywhere that what is on the slides is my original work. However, while I normally rely on several sources for my lecture slides, at times several slides in a row more or less summarise a few pages from the textbook/another source. Would I be expected to give a reference for this? [I should add that I do provide references if I borrow a whole chart etc. from a book].

I have to say that at least in the humanities and in my own career as a student and teacher, I have never seen such references. In fact, a criticism of students about some of my former professors was that they basically just go through the textbook in lectures. So, unless I am missing something, my guess is that I dont have to provide references [I dont mean what would be ethically "perfect" but rather what is accepted practice in academia]. However, now that I am doing it myself, I thought I could ask here just to make sure.
You should certainly cite your sources. Not for each and every use, a general statement like "Based on textbook and others" on your first slide (or slide of each class) should be enough. Add references to slides/classes as needed for people who want to dig deeper.