Archeology for Kids National Park Service pages designed for children to explore ideas behind archeological methods, careers, and discoveries.
Project Archaeology "Project Archaeology uses archaeological inquiry to foster understanding of past and present cultures; improve social studies and science education; and enhance citizenship education to help preserve our archaeological legacy."
The Missouri Department of Transportation has a short information page about archeologists and what they do. You may wish to check with your own state's Department of Transportation to see what information they can share with you.
The Society for American Archaeology has education pages plus very well documented tips and suggestions about commonly attempted programs, such as simulated digs.
Crow Canyon Archaeological Center has some excellent student resource pages on-line to explore archaeology and ancient pueblo cultures.