"Living in Water" is a classroom-based, scientific study of water, aquatic environments, and the plants and animals that live in water. The lessons in this curriculum integrate basic physical, biological, and earth sciences, and mathematics. The integration of language arts is also considered essential to its success. These lessons do not require a water monitoring program or access to an aquatic habitat, although it includes suggested field experiences for students. Several themes run throughout the curriculum, including control of variables in the design of valid experiments, the usefulness of models in understanding natural systems, application of knowledge in the design and testing of models, the collection and manipulation of numerical data, and identification of things using classification based on common characteristics. The curriculum is divided into six sections: (1) Living in Water: Aquatic Habitats-Freshwater, Estuarine, and Marine; (2) Things Dissolve in Water; (3) Temperature Changes and Aquatic Habitats; (4) Moving or Staying Put: Maintaining Position within Aquatic Habitats; (5) Light in Water; and (6) Wrapping It Up: Projects and Programs. Each section presents science content information as well as student activities. Lessons use various approaches and instructional strategies. (WRM)