Visions of Next Generation Science Standards-aligned instruction place high discursive demands on learners. Learners are expected to articulate, develop, and defend their ideas and respond to the ideas of others. Decades of prior research have carefully documented features, processes, and potential benefits and shortcomings of an emphasis on talk in science learning. Yet, the task of documenting change in learners' talk over time remains a major methodological challenge. To address this challenge, we examine one Korean immigrant girl's (Selena) oral participation during an informal science learning program called Science Club. Quantitative analysis showed that, over time, Selena spoke more often and for longer. However, fine-grained qualitative analysis of features of her talk (e.g., use of a variety of bids and hedges) demonstrated Selena's persistent desire to share ideas, even though the intellectual merits of those ideas went largely unacknowledged. Methodologically, Selena's case illustrates the importance of considering multiple features of learner talk, understood in the social context, when making claims about changes in oral participation over time. Pedagogically, Selena's case highlights the importance of teachers' attention to how learners' ideas are taken up, in addition to how frequently they are speaking in class.