MorgueFile.com is a morbid name for a useful resource. Despite what you might expect, this website does not contain pictures from a morgue. A morgue file is a term from the newspaper industry to describe paper files that are inactive and only kept for reference. Illustrators later adopted this term to refer to files of images that could serve as inspiration or reference. MorgueFile.com is a large collection of images that are contributed to be used for reference by artists and teachers.
Once you get past the name, this is a very useful resource. I was struck by a link on the homepage to a collection of photos of robot toys, including the one above. There are a total of 116 toy robots in this collection, which is really interesting to skim through.
Of course, toy robots may not apply to all of your teaching needs. Other searches revealed 66 photos labeled classroom, 234 photos labeled student, 734 photos labeled books, and 1190 photos labeled computers. Many of the photos are high resolution and have a very professional stock-photography appearance, by which I mean objects are on white backgrounds and scenes are generic enough to be useful in many situations. Next time you need an image for your PowerPoint presentation, consider an interesting and relevant photograph instead of canned clip art.