Because student activities are often restricted by inclement weather, this Unified Sciences and Mathematics for Elementary Schools (USMES) unit challenges students to predict weather to help them plan activities and schedules. The challenge is general enough to apply to many problem-solving situations in mathematics, science, social science, and language arts at any elementary school level (grades 1-8). The Teacher Resource Book for the unit is divided into five sections. Section I describes the USMES approach to student-initiated investigations of real problems, including a discussion of the nature of USMES "challenges." Section II provides an overview of possible student activities with comments on prerequisite skills, instructional strategies, suggestions when using the unit with primary grades, a flow chart illustrating how investigations evolve from students' discussions of weather prediction problems, and a hypothetical account of intermediate-level class activities. Section III provides documented events of actual class activities from grades 2/3, 5, and 6. Section IV includes lists of "How To" cards and background papers, bibliography of non-USMES materials, and a glossary. Section V consists of charts identifying skills, concepts, processes, and areas of study learned as students become involved with weather prediction activities. (JN)