This online learning module aimed at university-level students provides an introduction to GIS applications. It's available in English and French. It's based on a free version of Arc for educators and includes links to download.
Outline of a "community mapping experiment" syllabus for youth - appears suitable for middle school / junior high school students, most likely?
"The Community Mapping Experiment enables the students to "define" their community by using the GPS receiver to measure the position of some important landmarks."