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 teaching guide is designed for use with the 19 chemistry investigations found in the student manual. 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; zinc combinations; 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 includes activities related to the three learning cycle components (exploration, conceptual invention, and expansion of the idea). The guide contains: a list of chemistry concepts fostered in each investigation; detailed instructional strategies for student investigations, which are reproduced in the teacher's manual in reduced form; student reading questions and answers (the readings, however, appear only in the student manual); and lists of equipment needed to complete experiments. (JN)