The teachers' guide to this unit, prepared for use in grades seven or eight of Australian secondary schools, contains a list of unit objectives, teaching notes on each activity, lists of required apparatus, suggested teacher and student reference materials, and appropriate audio-visual aids. The core of the unit explores the importance of water for organisms, examines the water cycle, and provides data on the rainfall distribution in Australia. Students are expected to choose additional activities from nine options suggested. The options concern solution and suspension, water movement through aquifers, measurement of humidity with a home-made hair hygrometer, the thermal properties of water, ice formation, transpiration, hard water, survival in deserts, and problems of water pollution. All options are introductory and usually involve experimental manipulation. The student book contains the necessary instructions for the core and optional activities, a diagnostic test, and annotated answer sheets to the test and to questions asked in the activities. An expendable student record book with space for recording data and answering questions is provided. (AL)