Why should I start at the Grade 5 item set when I know the examinee can't read at a 5th grade level?
As is typical of a regular classroom setting, each Reading Comprehension item set is designed to span a range of reading skills. The Grade 5 item set, for example, has reading passages designed at the Grade 4 reading level, some at Grade 5 reading level, and some at Grade 6 reading level.
For qualitative purposes and error analyses, an examiner may choose to "test the limits" and see how the student performs on items beyond the grade-appropriate item set. This is an acceptable practice, as long as the additional items are not used in calculating the standard score.