Children can learn how to evaluate their work and reflect on it in a critical way. If you have been collecting students' work, have them look through their portfolio and select the items they are most proud of. Teaching students to go through this process helps them hone their skills when they write and edit their work. I came across these assessment sheets in my files. I do not know where they came from so I am posting them for free.
If you have seen these before and know their origins, please leave me a comment so I can give credit where credit is due!