A great way to get children motivated to experiment with writing non-fiction text is to relate it to something they are currently studying.
My students, fourth graders aged 9-10, have just finished reading the BFG by Roald Dahl. After studying an instructional text, in the context of the BFG, my students brainstormed ideas for sets of instructions that the BFG might write for human beings. For example, ‘How to Catch a Dream’, ‘How to Talk Like the BFG’, and ‘How to Protect Human Beans (beings) from Giants’.
My children were much more motivated to write those sets of instructions, rather than ‘How to Tie Your Shoe’ or ‘How to Get Dressed in the Morning’.