Can I use images from Google in a presentation for a class lecture?
We have conferred with Will Cross, the UNC Libraries Copyright Manager about questions like this (use of copyrighted images in educational presentations) in the past. I quote his reasoning below that this particular use would qualify as fair use:
"..there's a good case that using one or two images in a Powerpoint presentation is fair use. The educational purpose, small amount used and minimal market harm all cut in that direction. If the presentation is part of teaching in the university context it might also fall under the 110(1) teaching exception that permits display in this context."
So, your use of a few copyrighted images from Google as part of an educational presentation is probably fine from a copyright perspective. It is good practice to attribute the image in some way such as include a small URL below the image to the source or include a slide with "credits" at the end.
One other note and you may already be aware of this. In case you did not see it, the Advanced Search page in Google Image Search allows you to limit your search to images that are "Labelled for ReUse" by selecting that choice from the pulldown list for the "Usage Rights" field.