The purpose of this study was to investigate the relationship between the nature of small group discussion tasks and learners' talk during Physical Science lessons. The study was conducted during Physical Science lessons with three self-selected groups of Grade 11 learners from one school. A total of three lessons were followed. During the lessons, learners were given group tasks to complete, and their discussion was audio-recorded. The small group discussion tasks were coded using the revised Bloom's taxonomy. The audio-recordings were transcribed and coded using Mercer's three types of talk. The nature of tasks in the small group discussions was paired with the type of talk used as the group members were responding to the tasks and the frequency of these pairs was analysed. Analysis of the tasks vs. types of talk used indicated that learners predominately used cumulative talk to find solutions to understanding tasks. Exploratory talk was predominately used to find solutions to application tasks. The findings show that this relationship between the nature of small group discussion tasks and learners' type of talk is statistically significant at p = 0.05 level. No disputational talk occurrences were observed. It is noted that the type of talk used to address each type of task is related to the cognitive skills demanded by the task, group composition and the embracing of the spirit of ubuntu by the group members.