Last year, my son’s kindergarten class took a field trip to their local library. Each child was allowed to borrow one book. My son chose this:

The National Geographic Pocket Guide to Rocks and Minerals of North America.
It was admittedly not the most developmentally appropriate book for a kindergarten student, at least in terms of reading level. At the time, my child could only read a handful of words on every page, and most of the scientific language was completely beyond him.
Some librarians might have encouraged my child to pick a more traditionally level-appropriate title. A board book, perhaps, or a picture book or early reader. Something with fewer words and more pictures, that he would have been able to read independently. The problem with that logic, as sound as it is, is that my son loved, and still loves, rocks, and those other, easier books, probably wouldn’t have scratched his geological itch.

Thankfully, whoever this librarian was, they seem to share my general philosophy regarding “appropriate” books, which is that the right book for any child is a book that gets them excited about reading. And this book, all about identifying rocks and minerals, definitely got my child excited!

He wasn’t able to read this dense nonfiction title all by himself, of course. But he isn’t all by himself. He has supportive, involved parents and relatives who can and do read with him and to him. And even if he’d picked a book in a language we couldn’t read, we would look through the book together and talk about the pictures, perhaps making up our own stories about the different rocks and minerals presented therein. Once we discovered his obsession with rocks, we also made an effort to seek out simpler books on the subject that were intended for a child audience, so we could continue to support his interest and his reading skills.
All this to say – when encouraging your young readers, whatever their age, let their passions be your guide. Worry less about what “level” a book is, and more about whether the subject matter will appeal to the child, pique their interest and keep them engaged. Even if that means learning more about igneous and metamorphic rocks than you ever wanted to know!