The Zimbabwe Secondary School Science Project (ZIM-SCI) developed student study guides, corresponding teaching guides, and science kits for a low-cost science course which could be taught during the first 2 years of secondary school without the aid of qualified teachers and conventional laboratories. This ZIM-SCI study guide is a three-part unit consisting of activities and experiments in which students: (1) examine the nature, properties, and potability of water; (2) mix substances which produce solutions and suspensions; and (3) examine the solubility of substances and the rate at which they dissolve, prepare saturated solutions, and separate liquid mixtures. Information is provided throughout the unit to help students understand the scientific principles behind the activities and experiments. (JN)