ChemSource is designed as a strategy to help preservice and inservice high school chemistry teachers promote student learning more effectively. Its major premise is that well-designed laboratory investigations are an important avenue for cultivating student interest, engagement, and meaningful learning in chemistry. The SourceBook component of ChemSource is a resource containing 36 content modules and additional supporting materials which aim at providing specific teaching tips and the best available instructional ideas and information gleaned from experienced, successful chemistry teachers. Each content module features: Content-in-a-Nutshell; Laboratory Activities; Demonstrations; Common Misconceptions; Humor; Applications and Implications; Analogies; Reference Resources; History; and Media. General materials on pedagogy, classroom management, safety, teaching chemistry to the disabled, and other useful resources and tabulations precede and follow the content modules. Volume 4 includes the following: Chemistry of Seawater; Separations; Solutions; Stoichiometry; Thermochemistry; Transition Elements; Computer Uses; Chemistry in Your Career; Cross-Referencing Modules; Teaching Chemistry to Persons with Disabilities; Library Resources; Professional Organizations; Small-Scale Chemistry; and Chemical Safety. (JRH)