The argumentation lessons were taught towards the end of the genetics topic after students
had studied inheritance and some uses of gene technology including genetics testing and
genetic modification. The timing of the argumentation lessons was deliberate as it had been
shown previously that students of this age displayed better argumentation skills if they have
some prior knowledge (Aufschnaiter et al. 2008; Lewis and Leach 2006). Extensive field
notes were recorded during the professional development session, a pre lesson, and the
lessons on argumentation. Audiotapes of all lessons were transcribed. The transcript
sections where Mr. D promoted argumentation were coded using the framework developed
by Simon et al. (2006).