This USMES unit challenges students to recommend and try to have a new road design or a system for rerouting traffic accepted so that cars and trucks can move safely at a reasonable speed through a busy intersection near the school. The teacher resource book for the Traffic Flow unit contains five sections. The first section describes the USMES approach to student-initiated investigations of real problems, inlcuding a discussion of the nature of the USMES "challenges" and of classroom strategy for problem-solving activities. The second section gives information about the Traffic Flow unit, including an overview of possible student activities with comments on prerequisite skills, a flow chart and composite log indicating the range of possible student work, and a list of questions that the teacher might use. Section 3 contains documentation of class activities, describing ways of introducing the unit and including teachers' logs for the unit. Section 4 includes references to other written materials relevant to the unit and section 5 consists of charts which identify the skills, concepts, and processes covered by the unit.(DT)