The Biological Sciences Curriculum Study (BSCS) was established in 1958 with the mission to improve the quality of biology education at all levels. Not long after the inception of the organization, our mission was expanded to include the improvement of science education, not just biology education. In 2000, we further articulated this mission to describe the work we would do in curriculum development, professional development, and research and evaluation.
In this book—a handbook for biology teachers—you will be exposed to some of our tradition and some of our future. The tradition comes from focusing on the quality of biology education. The future comes from approaching the quality of biology education from multiple perspectives—instructional materials, teacher development, student learning, controversial issues, classroom management, and inquiry teaching.
The Biology Teacher’s Handbook was first released in 1960 as an experimental volume. The first through third editions were released between 1963 and 1978. In the mideighties, the book was taken out of print. We are grateful to the National Science Teachers Association (NSTA) for having the foresight to understand the value of a handbook for practicing teachers. Because of NSTA, we are able to launch the next generation of this publication.
The world of the classroom is more complex than in 1958, when BSCS began its work. More than ever before, teachers have to attend to a greater range of discipline challenges, multiple native languages, an exploding volume of new content, and highstakes testing. In this handbook, we have done our best to acknowledge the challenging 
environment in which you work, while providing the scaffolding to help you be the kind of teacher who enables every student to learn as much as he or she is willing to.
BSCS is first and foremost a research and development organization. We do our best to translate research into practice. This handbook fully represents that philosophy; however, just because the pages are bound between a cover does not mean this is a finished product. At a curriculum study, we do our research, in part by listening to the practitioners in the field. As you use this handbook, do not hesitate to let us know what was useful, what was not useful, what you found missing, what you found redundant. Please go to handbook.bscsonline.org to make your comments and suggestions. We will address your suggestions in the next edition.