Is it better to lecture with a board or a document camera?
The issue of how technology effects communication and learning is definitely of interest, from a linguistics perspective or from an educational perspective.  Most importantly, at the chalkboard it is easy to point.  A document camera allows pointing, but it is awkward.  Tablets make pointing very hard (I learned this the hard way).

This is not at all my area, and I have not vetted the following papers.  They look interesting, and perhaps give you a start in accessing the literature.  Mostly I found studies of tablets, but did find one discussing the advantages of a document camera for some students with disabilities.


Maclaren, Peter, David Wilson, and Sergiy Klymchuk. "I see what you are doing: Student views on lecturer use of Tablet PCs in the engineering mathematics classroom." Australasian Journal of Educational Technology 33.2 (2017).
Maclaren, Peter, David I. Wilson, and Sergiy Klymchuk. "Making the point: the place of gesture and annotation in teaching STEM subjects using pen-enabled Tablet PCs." Teaching Mathematics and its Applications: An International Journal of the IMA 37.1 (2017): 17-36.
Williams, Jocasta, and M. F. Fardon. "Lecture recordings: extending access for students with disabilities." ALT-C. 2007.