This covers what a population pyramid is, and how to analyze one. It covers the three basic shapes and how they correspond to population growth or decline.
Simple introduction on how to analyze population pyramids. Update: some these slides originally came from a different presentation, which has since been revised. You can find the revisions at: http://houstonhs.scsk12.org/~mrobinson/Mr._Robinsons_Web_Site_at_Houston_High_School/June_Presentation.html (paste in full URL)
Via Seth Dixon