"Intelligent Books" are Web-based textbooks that combine computer-supported exercises with content that is both adaptive and extensible. They impose very few restrictions on the kind of exercise that can be placed within the book, and they allow students to contribute material that they have written, and to incorporate material from the Web into the book. In this chapter, the authors describe the influences that affect the design of intelligent books. These come from looking at the roles that textbooks and course notes play in education, and economic factors that affect the sustainability of intelligent books - competing for the attention of users, and ensuring that network externalities do not prevent a sufficient quantity of material from being usable within the book.

Intelligent Books are Web-based textbooks that can adapt and improve their content and guide students through graphical example exercises that resemble the diagrams and notations a student might use on paper. The exercises use formal AI systems to analyse students' work, and different AI systems are used for different questions. This brings the issue of how a person can write questions if they are not an expert in the AI system used. We describe our experiences developing an authoring tool for electronics questions that use a specialised circuit AI with its own extensive circuit language. The tool works on the principle of exposing an appropriate visual model of the AI, while factoring out the language detail and the architecture of the book itself, and allowing the question writer to decide which parts of the AI model to expose to the student (as the desired mental model for the student).

We have developed a web-based homework tutor for discrete mathematics that is a step of progress towards building an intelligent adaptive textbook. The student works on mathematical problems in a notation that is closely mapped to the notation the student would be expected to write on an exam paper. The tutor gives advice and feedback as the student is working, in a co-operative manner rather than submission-and-response. This feedback is linked into the topic structure of the intelligent book, allowing the student to query for content material relating to a piece of advice. More than one content item is available on any topic, allowing server rules to choose items the that are likely to be useful to the individual student, while still allowing the student to reject the tutor's selection and choose a different content item.

The Intelligent Book project aims to improve online education by designing materials that can model the subject matter they teach, in the manner of a reactive learning environment. In this paper, we investigate using an automated proof assistant, particularly Isabelle/HOL, as the model supporting first year undergraduate exercises in which students write proofs in number theory. Automated proof assistants are generally considered to be difficult for novices to learn. We examine whether, by providing a very specialized interface, it is possible to build something that is usable enough to be of educational value. To ensure students cannot "game the system" the exercise avoids tactic-choosing interaction styles but asks the student to write out the proof. Proofs are written using MathsTiles: composable tiles that resemble written mathematics. Unlike traditional syntax-directed editors, MathsTiles allows students to keep many answer fragments on the canvas at the same time and does not constrain the order in which an answer is written. Also, the tile syntax does not need to match the underlying Isar syntax exactly, and different tiles can be used for different questions. The exercises take place within the context of an Intelligent Book. We performed a user study and qualitative analysis of the system. Some users were able to complete proofs with much less training than is usual for the automated proof assistant itself, but there remain significant usability issues to overcome.