The comprehensive or `B' exams are written tests given at the end of each semester, in January and May. There are eight exams, and they do not have to be taken together. Preparation for exams mostly consists of taking the appropriate courses. However, the exams may contain material not covered in any class. You should consult the syllabus and make sure you are familiar with all the material it covers.
Students are encouraged to take these exams seriously and pass them as quickly as possible. Students must pass at least five of the exams exams by the end of two semesters. Failure to do so is the most common reason students are ejected from the PhD program. A student may petition for an extension, but petitions will be approved only in extraordinary circumstances. Take your B exams very seriously!
Students who pass seven out of the eight exams will have no further obligations with regards to the B exams. Students who pass six out of eight exams will be required to take one additional course in each of the two areas that they did not pass and to get a grade of B or better in at least one of these two courses. Students who pass only five of the eight exams will be required to take one additional course in each of the three areas that they did not pass and to get an average grade of B or better in at least two out of the three courses. The courses students shall be required to take will be decided jointly by the Chairman of the Graduate Committee and the Chairman of the Examination Committee. Students must complete this course requirement by the end of their fourth semester.
Since the B exams are offered at the end of each semester, students with strong backgrounds are urged to come to Rice in May and take some or all of the exams before the start of the Fall semester. Each exam you pass means one less you'll need to study for in the future.