Technological pedagogical content knowledge (TPACK) proposed by Mishra and Koehler is a theoretical construct of teacher knowledge that describes how teachers teach subject matter content using certain instructional methods with specific technology in particular contexts. This study aims to explore the interface between TPACK and SLA, intending to examine (a) how a Taiwanese English teacher enhanced L2 interaction and (b) how her students perceived such teaching. While data regarding the teacher's TPACK-SLA knowledge was collected through lesson plans, classroom observations, and interviews, data associated with students' perceptions was obtained through a questionnaire survey and focus-group interviews. The findings suggest that the teacher enhanced L2 interaction by(a) drawing students' attention to grammatical patterns through annotated animations, (b) consolidating vocabulary use through image-based exercises and a bilingual concordancer, and (c) evaluating the use of sentence patterns through text-chatting with a chatbot. While the students could improve learner-computer interaction through obtaining enhanced input, they could also develop inter-personal communication competency through negotiating meaning. In addition, the students appreciated the ways their teacher taught English using "Cool English." This study contributes some empirical insights into how EFL teachers can draw upon practices explored in instructed SLA to develop TPACK.