In this paper, the entries of Lang-8, which is a Social Networking Site (SNS) site for learning and practicing foreign languages, were analyzed and found to contain similar rates of errors for most error categories reported in previous research. These similarly rated errors were then processed using an algorithm to determine corrections suggested by a native speaker. Subject matter experts then evaluated the processed sentences to determine the quality in relation to use in tests or exams for language learners. The method describes the automatic generation of multiple choice and fill-in-the-blanks quizzes using the writings of language learners on public web based learning sites, in order to support learner reflection on corrections and practicing past errors to overcome problems.