while these books are not a direct tie in with grade5 units, I've used them in fifth grade and the kids have enjoyed them. I'm sorry I can't recall the exact titles, but there is a series of books with Sir Cumference in the titles. The one I received most recently (from Scholastic Book Clubs) has to do with the idea of finding pi by looking at many circles, measuring the circumference and the radius and finding some "magical" way to write an equation for all circles. I did this activity a few years ago, using a different Sir Cumferance book by tracing different circles, folding them in half, then in half again to find the radius, measuring the circumferance with string and then calculating the circumferance using the formula (giving the thevalue of pi as 3.14) This was really a great activity and the kids loved it.
