Can you link to exactly the page with the 5th grade assessment? Would we need to go through an entire 5th grade assessment to see if we feel like it is appropriate for grade level?

My dd10 is also a 5th grader, but in a 6th grade math class so I have some idea of what 5th and 6th grade math look like, but I do think that it differs from school to school and state to state. Maybe it would be worth taking a look at something like ixl's list of 5th and 6th grade math state standards (http://www.ixl.com/math/standards/) -- click your state and then the grade level -- or World Book Encyclopedia's list of what is typically taught in 5th and 6th grade (http://www.worldbook.com/typical-course-of-study.html). That might give you an idea of whether he knows a lot of what 5th grade math covers.

Also, his teacher might be able to give you a scope and sequence for what they intend to teach this year. Has he taken any other math assessments through school such as MAPS?