What are the advantages and disadvantages of using posters at school?

If you are a student, then a poster can add visual interest to your topic and help to keep you audience focused on the message of your presentation. If you are a teacher, posters can help make learning fun because they allow some creativity (and if done in class, they can eat up some time.) Many people use the free poster tips and tools at http://www.artskills.com to help them make better poster designs. There is even a free poster design book being given away on their site.