From the recently launched SmithsonianEducation.org Web site comes an excellent set of learning resources based on Exploring Marine Ecosystems, a permanent exhibit at the Smithsonian's National Museum of Natural History. The activities and lesson plans in Contrasts in Blue help students explore two distinctively different marine ecosystems: the Caribbean coral reef and the rocky coast of Maine. The Web site provides a detailed introduction complete with hypertext links for exploring specific concepts in more detail. The lesson plans "encourage students to consider the role of temperature, sunlight, waves, and tides in the creation of unique marine environments," and include downloadable worksheets.