Our "Water" unit of the activity guide contains various lesson plans, most of which take 45 minutes to an hour to complete (although some only 15-30 minutes), and targeted mainly at 4th-6th grade students. Most of these lessons focus on learning about the water cycle and the Everglades watershed. A class doesn't need to complete every lesson in the unit, though some lessons do refer to one another and are better done in sequence. Each lesson comes with its own set of objectives and resources.
Robinson, George B. & Robinson, Sandra C., Discover a Watershed: the Everglades, The Watercourse, ©1996, pp. 5-17.
Lodge, T.E., The Everglades Handbook Understanding the Ecosystem, CRC press LLC, ©2005