The focus of this study was to answer the following overarching question: How does a Twitter discussion format compare to a Facebook discussion format in terms of promoting collaborative argumentative discourse? Data analysis focused on the difference in amount of arguments, counter-arguments, reasons, and elaborations generated by participants between the two social media platforms. In addition, the impact of participant use of sentence openers on the amount of argument components was also examined. A Mann-Whitney statistical test was conducted to determine the differences between Twitter and Facebook groups in argument components across three small group discussion questions. The results of the test revealed there was a significant difference in the amount of argument components per discussion between Twitter and Facebook groups, with the Facebook groups including more argument components within their discourse. In addition, 15 participants were provided with a list of sentence openers. A content analysis was conducted on 319 tweets//postings. Although zero participants utilized the list, of the 15 participants provided sentence openers, 7 used variations (47%), with 5 in Facebook groups. Of the 12 participants not provided sentence openers, 4 used variations (33%), with 2 in Facebook groups. There was a small qualitative trend for the sentence opener groups to use variations, especially the Facebook participants. Based on these results, Facebook was identified as a viable tool to promote collaborative argumentation within an online discussion. What the results of this study determined is that the use of Facebook could be effectively incorporated into a full-semester online course
