Investigations in Natural Science is a program in secondary school biology, chemistry, and physics based upon the description of science as a quest for knowledge, not the knowledge itself. This student manual contains the 19 chemistry investigations. These investigations focus on concepts related to: interactions with water; salt and calcium; physical properties; heating and cooling a pure substance; composition of a compound; atomic theory and matter; lead nitrate and potassium iodide; combinations of zinc; hydrogen peroxide and manganese dioxide; mass relationships; temperature changes and dissolving; properties of ionic substances; Arrhenius solutions; pH, acids, and bases; acid-base interaction; salts and water; characteristics of methanol; solubility and structure; and periodicity and reactivity. Each investigation (which is accompanied by one or more readings with questions to answer) includes activities related to the three learning cycle components, namely, exploration, conceptual invention (the idea), and expansion of the idea. (JN)