National Council of Teachers of Mathematics. 1906 Association Drive, Reston, VA 20191-1502. Tel: 800-235-7566; Tel: 703-620-3702; Fax: 703-476-2970; e-mail: orders@nctm.org; Web site: http://www.nctm.org/publications/
Creating effective mathematics lessons can be a challenge for any teacher. One approach to design an effective lesson is using a before-during-after (BDA) format. This article describes what a BDA format is and provides two examples of how it is implemented in high school mathematics classes. (Contains 2 tables and 5 figures.)