Students are not proficient at 'reading' images even as they are so compelled by them. They don't often assign bias to image creators, electing to think of images as the ultimate truth.
Searching images can be difficult because what you find relies upon how people describe their image or what words appear elsewhere on that page.
Searching for images is a good place to talk about metadata - or, how people describe things so that they can be discovered. You'll likely find that students enjoy talking about how we or 'they' (maybe the media) describe things and how that relates to issues of identity.
Students often forget that images need to be cited.
Students often forget that images are intellectual property and are subject to copyright laws.
When you search for images on the Web, what problems do you run into? How have you had to edit your keyword search to retrieve the images you want?
How do authors use images to convey their message? Can you think of some examples?
How can you use imagery to invoke emotion and sway an audience to your viewpoint? Can you think of some examples?