Create a journal for your child by folding a stack of white construction paper in half and stapling it down the fold to create a booklet. Write the child's name on the front of the book to personalize the journal.
Discuss the process of writing in a journal with your child prior to using the journal with him so he knows what it is for and how he is to use it. You may find it helpful to talk about journaling with your preschooler for a few weeks prior to using the journal, or modeling how to use a journal by having him watch you use a journal yourself.
Establish a journal-writing routine with your child so that she'll learn to expect "journal time" each day. Give your preschooler crayons and her journal and give her the freedom to draw or write whatever she is thinking or feeling. Don't guide her journal entries—children need to be free to draw or write whatever they want in their journals.
Help your child express any written thoughts by discussing his journal entry with him when he is done. You may want to label drawings or write certain phrases specific to the meaning of the journal entry based on what he says about his work.