Boy should definitely be taught in the same year.  I find that kids without a pretty good knowledge of Apartheid get frustrated with textual elements that they don't understand.

Of course, the English teacher can always give historical background (I do, and love doing it)!  The teacher should consider the ability of his/her students to understand the complex ways in which Apartheid legislation actually affected individuals.

A thought should be given to graphic content, especially the "prostitution scene".  I decide whether or not to teach the book to a given class by deciding if the students can handle this question (in terms of maturity and analysis):

Mathabane notes that child prostitution was a known practice in the townships.  If parents like Johannes' know about it, why aren't they keeping a closer eye on their children?  Why aren't they getting together with other parents to prevent it?

"Kaffir Boy" is writen on the 7th grade level.  Who should read it and who should study it would greatly depend on how well a student reads, how mature the student is and how active the teacher and parents are in the analysis of the book.  I might also add a great deal depends on what area of the country one lives.  In a small rural town where people are over all more conserevitive, the teacher might be better off not to think about teaching this book until the Jr. or Sr. year in high school because of the uproar parents might create in lower grades.  On the other hand, if it is a large school system, especially in the Northeast, a school system might even have this in their Jr. High school library.  The words, "anus," and "penis" will send some student's and parents through the roof, while others can accept the fact that for their children to know what is going on in the world, their children might have to hear some biological terms.