The idea for creating dynamic online teaching maps came up after one of our teacher friends expressed her frustration over how difficult it was to find just the right learning map for particular topic. Her options were limited to existing workbooks with clear but overly general maps, photocopies of atlases that come out dark and overly complicated, and printing out bitmapped screenshots of maps from programs like Encarta. We think these map units can provide a good tradeoff between those three options.