favorite extra-curricular books for 4th & 6th graders?

[TMarie]

Relatives have asked for titles to send to the kids...
Could you share some of your favorites?

[ThelmaLou]

I have a handful of books I always want to work into school, but don't really fit into a specific subject area . I don't know if this is what you mean, or not. Two that my oldest read and really enjoyed include:

Neale S. Godfrey's Ultimate Kids' Money Book
The Everything Kids' Money Book

He learned a lot about savings, checking, electronic banking, investing, credit, stocks, etc...

[Lizzie in Ma]

The Sister's Grimm series is a new favorite and she adores Calvin and Hobbes
I am keeping in mind that you did say extra-curricular!
She also devours the American Girl books, anything about Robin Hood and King Arthur and anything along the lines of Indian Captive by Lois Lensky. Moccasin Trail, The Cabin Faced West, oh, the Rowan Hood series (because she loves Robin Hood AND Rowan is her name)
She has read and reread everything by Gail Carson Levine, who write Ella Enchanted including the book on creative writing.
I have just planted a few of the "Horrible Science" books about, waiting to see if those are a hit with her.

[Stacia]

The Dangerous Book for Boys or The Daring Book for Girls. Gave my nephew (6th grader) the boy one last fall for his birthday & he still is using/talking about it. Dd (4th grade) got the girl one this winter & loves it. She & her cousin have comparied the 'essentials' lists & so on from the books. Lots of fun, imo.