In this study, Modular Object Oriented Dynamic Learning Environment (MOODLE), an open-source Learning Management System (LMS) developed by Curtain University of Technology in Australia, was customized for essay writing classes in Korean. The subjects were 18 elementary school students who participated in an essay writing program over 6 weeks. Using a case study approach, the study reports some important lessons learned from the use of MOODLE to design blended, collaborative learning environments for elementary essay writing. Some important contextual factors and content-specific constraints that affected the student learning process are discussed.