The possibility of exploiting technology for more robust and meaningful learning and teaching has invoked messianic responses from the language education community. Yet to be explored are teachers' pedagogical choices based on the perceived technological affordances as well as interactions between teacher and student agency mediated by these affordances in the ecology of a classroom. This qualitative case study adopts an ecological approach, aiming to address rather than factor out the broader social context in a physical classroom. With data collected from 30 hours of classroom observation and 10 post-observation interviews with the participant teacher, the study makes an attempt to show how the ecological model of language learning can provide a theoretical lens through which to explore teachers' practices of CALL that aim to encourage learner agency. The analysis centers on three focused extracts that illustrate interaction between and among the affordance of technology, the teacher participant's pedagogical considerations, and her goal of encouraging learner agency. The result of the study emphasizes the teacher's role from an ecological perspective and classroom learner agency mediated by technology, which provides useful insight that can contribute to language teaching practice with technology in the classroom.