https://eee.uci.edu/00f/07211/pptweis1/weisppt5/sld001.
htm
The thing that defines a gametophyte is that it is a multicellular, haploid
structure that produces gametes mitotically.
The ovule is part of the sporophyte structure, and is composed of diploid
cells.
One of those diploid cells, the sporocyte, undergoes meiosis to produce the
haploid cells of the embryo sac.
On slide 10 the labeling for the ovule is wrong. The pointer is pointing
to the embryo sac, but the labeling says "ovule" and says the ovule is
the female gametophyte, which it isn't.
The rest of the slides are correct. In slide 13, the embryo sac
INSIDE the ovule is correctly identified as the female gametophyte.