This publication provides information and activities for teaching about water, whether certain objects will sink or float, and process skills including observing, classifying, inferring, measuring, predicting, and collecting and interpreting data. There are 14 lessons in the unit. The first four lessons deal with the classification of objects and placing objects in serial order. Lessons 5 and 12 pertain to vocabulary development using crossword puzzles. Lessons 6 through 9 involve floating sinkers and sinking floaters, building clay boats, things that float, and why things float. Lessons 10, 11, 13, and 14 are designed to teach the concept of density. Also contained in this unit are: (1) a list of materials needed for activities; (2) a list of objectives by lesson; (3) teacher background information; (4) worksheets and two quizzes; (5) additional activities; and (6) reproducible take-home pages of activities. (RT)