[grepLeigh]

Some of these might be less interesting to a boy at that age, but here are the books/authors I loved around 9 (lots of talking animals, magic, and adventure/detective plots):

Garth Nix Sharon Creech Scary Stories to Tell in the Dark Jane Yolan David Clement-Davies E. L. Konigsburg Louis Sachar Avi Brian Jacques Louise Erdich Edward Bloor Susan Fletcher "Reader Beware, You Choose the Scare" Goosebumps (like Choose Your Own Adventure but more modern at the time).

I grew into the kind of avid reader that still reads 50+ books a year. My Mom didn't try to control what I read, even if it was complete junk.

I also adored fact books like the coffee tables you mentioned. I remember having a pulpy "100,000 weird facts" book, both covers torn off because it was used so much. This was before Wikipedia.

[octobus2021]

(I'm going to assume you meant "interesting to a boy as opposed to a girl". If I'm incorrect my apologies).

I only have boys so do not have personal experience but I read/heard that girls do and will continue to read more than boys at any age, and the gap is getting worse starting around that time (7-8-9). I do think that some books are directed at girls, but I do see a lot of books directed at boys too (though not recently, Hardy Boys was a loooong time ago). It's just boys are less interested regardless. Not really sure what to do about that honestly...