As a teacher I am always looking for innovative ways to get students more involved in their own education. Blogging about classroom activities, content learned and questions they have would be a great way to get kids involved in their own learning while growing as 21st century learners. Plus it would be a great way for parents to find out about what their students are learning and to get to know their child as a student even better.
There are lots of great blogs out there for kids. To start check out:
http://onlineschool.net/2009/10/27/100-best-book-blogs-for-kids-tweens-and-teens/ a great article with loads of great links for student blogs.