Check out the Atlas of Urban Expansion for a quick interactive website concerning urban sprawl. Assign one city per student and have them compare.

From the website: The NYU Urban Expansion Program at the Marron Institute of Urban Management and the Stern School of Business of New York

University, in partnership with UN-Habitat and the Lincoln Institute of Land Policy, has initiated a multi-phase research effort to monitor the quantitative and qualitative aspects of global urban expansion.

This effort is a continuation of an earlier project by the authors and their colleagues that resulted in the Atlas of Urban Expansion (Cambridge MA: Lincoln Institute of Land Policy, 2012). The monitoring program has now completed the data collection and has begun the interpretation and analysis of the data in three interdependent phases in a global representative sample of 200 cities.

The website includes historical urban sprawl clips for a bunch of cities.