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.