L earning a scientific discipline such as biology is a daunting challenge. In a typical advanced high school or introductory college biology course, a student is expected to learn about 5000 concepts and several hundred thousand new relationships among them. 1 Science textbooks are difficult to read and yet there are few alternative resources for study. Despite the great need for science graduates, too few students are willing to study science and many drop out without completing their degrees. New approaches are needed to provide students with a more usable and useful resource and to accelerate their learning.The goal of the Inquire Biology textbook is to provide better learning experiences to students, especially those students who hesitate to ask questions. 2 We wish to create an engaging learning experience for students so that more students can succeed -and specifically to engage students in more actively processing the large number of concepts and relationships. Inquire Biology aims to achieve this by interactive features focused on the relationships among concepts, because the process of making sense of scientific concepts is strongly related to the process of understanding relationships among concepts (National Research Council 1999). To encourage students' engagement in active reading, our pedagogical approach is to help a student to articulate questions about relationships among concepts and to support them in finding the answers.Inquire Biology incorporates multiple technologies from the field of artificial intelligence. It includes a formal knowledge representation of the content of the textbook, reasoning methods for answering questions, natural language processing to understand a user's questions, and natural language generation to produce answers. It is based on a systematic knowledge-acquisition process that educators can use to represent the textbook's knowledge in a way that the computer can reason with to answer and suggest questions. A unique