Teaching children to successfully read non-fiction is often a forgotten skill. It seems like we think if they can read fiction. . . they certainly should be able to read non-fiction. That is not necessarily true. Learning to read non-fiction is an important skill that we need to help our children develop.
Below are a a few ideas that may be helpful.
For preschool, kindergarten, elementary students I recommend simply reading non-fiction to them and talking to them about what you have read together. Some further ideas to help with comprehension would be to have your student draw pictures of what they have read, write a one or two sentence summary, or tell you what the passage was about. (narration).
For Kindergarden/first grade students you can make a simple list of what they want to learn about a topic before they read a book. That gets the student to actively engage their mind before reading. Check the list at the end to see if any of the questions were answered.
A more advanced method for older students is the KWL chart. There are different variations, but this is a basic one. Write what you know about a topic, what you would like to know about a topic, and after you have read what you have learned. I think it is a very good method to reading non-fiction.
Another graphic organizer for Elementary and middle school is the super six method. The student writes down six things they have learned while reading a non-fiction text. I would let the student know you will be asking them to do this after they finish reading a selection before they read it.
Lastly, for junior high students and high school students a great method for reading a text book is the SQR3. SQR3 stand for Survey, Question, Read, Recite, and Review. This article discusses the method in detail and is a great resource. I think it is very helpful for high schoolers to have a plan when reading a text book. We often assume our students can do this when they are not sure where to even start. I believe this is an essential skill for older students to learn.
Hopefully this is a good place to start. Being intentional and teaching our students how to read non-fiction is critical to their education. It is a skill they will carry with them throughout their lives.