Despite a sustainable research interest in the effectiveness of classroom instruction and delivery, the research on lesson planning against the changing educational landscape does no suffice, especially when Chinese New English Curriculum is proposed throughout the country. Based on a qualitative research design, this study explores some context-responsive practical issues in lesson planning. The study was conducted with 6 teachers of English as a foreign language in southern China. Data were collected through the semi-structured interviews, classroom observations, and teaching documents. Underpinned by Complexity Theory, the participants' understanding and practice of lesson planning, classroom activity planning, assessment, use of technology and teachers' collective agency were analyzed. In particular, findings show that, to align the new curriculum, the participants exhibited their initiatives and creativity in lesson contextualization, sequencing, maximization of resources, tapping on technology, and exchanges and collaboration with their colleagues or education experts. The study argues teachers' situated practices and policy-supported practice contribute favorably to teachers' lesson planning and professional development.