Uncle John's Bathroom Readers fill this gap. This is trivia at its finest, with short but detailed articles on pretty much subject under the sun, and including the sun itself. Usually no more than 5 pages per article, they allow for picking and choosing what stories you want to read.
Lest you be concerned that trivia books are a nerdy pursuit (they generally are) there are different types of Readers that will appeal to various types of boys: general information that covers everything you can think of, but also specific titles as in the image. TV, General Sports, Movies, Music, Oddities, National Parks, Canada, Hockey, Baseball, various US States, Science, etc. There are dozens of titles. You may already know of the spin-off "For Kids" versions.
I started reading these when I was a teen visiting my grandparents house and not having much to do. They had stacks of these books, and I was engrossed, usually spending more time reading them than visiting. Now I have a large collection of my own.