The College Board website actually list all the "advanced topics" as well as describe the types of questions covered in each of the three subscore categories. You can get detailed reviews on specific questions online for free as well as the four official tests at the college board website if you don't want to use the khan academy site. DS was only half-way through Algebra 2 and did not need anything more than that and a quick review of the advanced topic chapter. Doing two of the practice tests helped as well for timing purposes and to learn the advanced topics he didn't know.
