School Clip Art - Hundreds of Free Files for Students

School Clip Art is, as the name implies, a resource for locating free school-safe clip art. School Clip Art's galleries contain hundreds of files that teachers and students can use in slideshows, videos, and other digital presentations. You'll find galleries for sports, seasons of the year, holidays, and other special occasions.

Applications for Education
If the standard clip art that comes with PowerPoint or Keynote doesn't have what you're students need, have them browse through the galleries of School Clip Art.

Here are some related items that may be of interest to you:
NASA eClips
Open Clip Art Library