Vicki:
One nice feature of Google is that you can specify the search results
should be PowerPoint files only.
Along with whatever search terms you are using, add this:
filetype

PT
The word "filetype" and a colon and the letters PPT. No spaces.
FYI: This also works for PDF, DOC, PS, XLS, RTF. More details here:
http://www.google.com/advanced_search?hl=en
Hope this helps. Report back with what you found and share it with the
rest of the class. You will be graded.
Tony Ramos, PPT MVP
Specialist in PowerPoint Presentation Design
http://tonyramos.com
Home of "Tony's PowerPoint Weblog"