The potential of a paperless classroom cannot be achieved unless a context is created for collaboration and sharing of paperless content. A class blog is perfect for fulfilling this role. A class blog is free and easy to use and, more importantly, it gives students and teachers the opportunity to create and share paperless content. In addition, most blogs have a comment function, which allows students and teachers to interact with their audience. To capitalize on smartphone ownership and encourage students to participate in real-time conversations, the author experimented with the micro-blogging software, Posterous® Spaces. This paper will share a brief report on experiences using the software at three Japanese universities and describe how students participated on their mobile devices.