There are nonfiction books for all age groups. These include biographies, autobiographies, books on countries, animals, history and other factual information. These are often illustrated or contain photos.

Nonfiction publications frequently have a higher word count than their fiction counterparts for the same age group.

 

Examples
2- to 5-year-olds

Welcome to Our World: A Celebration of Children Everywhere! by Moira Butterfield

 

6- to 9-year-olds

Super Cool Space Facts by Bruce Betts

 

Middle Grade

5,000 Awesome Facts (About Everything!) by National Geographic Kids

 

YA

The Boy Who Harnessed the Wind by William Kamkwamba and Bryan Mealer