I have my students write for the first 5 minutes of class, although it sometimes varies if we need the 5 minutes for whatever we are doing in class that particular day. Task to do immediately upon entering the class. Gets ready for writng for the class period. Teacher has extra 5 minutes to prepare or organize. Students can confide in teacher, giving them someone to talk to about things.
Students can keep personal ideas.
I use my journal in a different way than other teachers I know. My students are sometimes given specific topics tow rite about and sometimes they are free to write about whatever they wish. The key is to write for five minutes, not talk to a friend or stare out the window. We sue this as a communication piece. I read their entry, write back to them on the same page, and they can continue that if they wish.