Blog for students

Create a blog which will be written by different students (learning English) each day. Each student will take turns to write the blog of the day, and will be working from their home/office. Ideally they should not require any special software (in companies, they are not allowed to install software). Example: Student A (with own username and password) will write blog on Monday, Student B on Tuesday etc. All students can view and add comments to the blogs in the normal way. Sound: if possible (assuming the Student's computer is equipped with a microphone) they should be able to add a sound file to their blog). As the teacher, I should be able to make simple adjustments to the appearance of the blog. This blog is for one 'class'. Ability to create additional classes/sets of students.