Recognizing basic elements as building blocks is essential to the study of science, and looking closer at one element in particular, chlorine, can help ignite students' interest in chemistry. This document contains a 2-day study of building block chemistry using basic concepts and easy-to-find materials. Teaching materials include objectives, safety notes, disposal of solutions, teaching strategies, sample student data table, chlorine background information, chlorine chemistry and product tree, and student worksheets. (MKR)