Blogging with Students in Classroom

After doing the book readings and looking at some comments it does seem students would be interested in, able, and willing to blog as part of the classroom curriculum. They want to share their ideas and experiences to others but as the classroom teacher you would have to make sure the blogging is acceptable and safe. This would require a good amount of prior approval, planning, and testing from the teacher so all does go as planned out. With the economy and cut backs this would be a great way for students to post work, test answers, etc. so we could go to a paperless style of communicating and displaying classroom information which would save money. The positives of doing Web Blogs are many such as it expands the walls of the classroom,is a democratic tool that supports different learning styles, and can enhance the development of expertise in a particular subject. The question I have now is why has this style of teaching and communicating not made more strides into more classrooms?