I also love writing down favorite quotes, lines from books, sermons, and revelations I feel God is speaking to me. I am a visual and tactile learner, so in order for something to really stick with me I need to hear it, write it, and reread what I wrote. If I just listen to a sermon or just read a book, I am less likely to retain the information. I love highlighting or underlining books for this reason as well.
I have Sitora journal for this very same purpose. I want her to be able to express her feelings, emotions, and process life in this way. If she grows up and doesn't care for it anymore, at least I gave her the opportunity and the tools to learn how to process what God is doing in her heart.
I have encouraged her to draw pictures and write what she is feeling in her journal, but she insists that for now she wants to copy her Bible word for word in her journal. I have always told her that Jesus will lead her if she asks Him to, so I have to trust that this is Him leading her. I never once suggested to her to copy her Bible passages in her journal, she just came up with it on her own. She picked her current favorite Bible story to start with and has been working in it for quite some time! She is using The Jesus Storybook Bible and is copying this story (it is written in a more kid friendly way but this is the scripture it is based upon):