In each debate, approximately three students largely dominated the interaction in terms of numbers of mes- sages (14–18 messages). Some students did not inter- vene at all.
From Fig 5, it can be seen that in each half-class, category 123 (off-task, social talk, and interaction management) largely dominated the debate, as with the small- group debates. However, in the present case, this is largely explained by the fact that 12 and 9 participants had to log on to the chat, and thus make greetings that were replied to, as well as to log off and close the inter- action. Therefore, contrary to the small-group debates, in the moderated class debates, there were almost no ‘123’ (off-task) interventions once the debate had actu- ally begun.
It is clear, therefore, that these teacher-moderated debates were much more argumentative than the small- group debates. In the latter, ‘123’ interventions could comprise up to 90% of the interaction (Fig 3). In the half-class-moderated debates, this was generally almost halved, and, correspondingly, the argumentative cat- egories were approximately doubled. However, the stu- dents’ arguments were, again, very little elaborated: in sum, they were very short (in accordance with the first ‘s’ of ‘SMS’, ‘short message service’) and were largely still written in slang.
This teacher-led debate sequence seemed to keep the students on the topic, while not always changing the slang abbreviated form in which they wrote. In each sub-debate, the teacher made very few interventions, mostly asking the students to start debating and asking probing questions. It seems that teacher moderation in a whole-class discussion made the students remain at least on the topic to be debated, although it did not lead the students to really elaborate their arguments nor to frame them in school-preferred language.