Engaging children in argumentation-focused discussions is essential to helping them collaboratively make sense of scientific phenomena. To support this effort, teachers must listen and be responsive to students' ideas to move the discussion forward with the goal of reaching consensus. Given the complexity of this ambitious science teaching practice, in lieu of traditional field experiences, online simulated teaching experiences provide opportunities for preservice teachers to practice implementing these strategies in a low-risk, high-support environment. Limited research has explored elementary preservice teachers' responsiveness while navigating an argumentation-focused discussion, particularly in an online simulated teaching experience. The purpose of this study was to examine preservice teachers' responsiveness to students' ideas while eliciting students' initial constructed arguments and encouraging argument critique in two online simulated teaching experiences. Findings showed that preservice teachers' responsiveness to students' ideas was high in both online simulated teaching experiences when asking students to share evidence as well as engage in critique. However, their responsiveness varied when prompting for reasoning and was often low when eliciting students' claims. These findings provide empirical evidence that such online simulated teaching experiences can be used as productive spaces for PSTs to practice being responsive to students' ideas during argumentation-focused discussions.