Dialogic, sense-making interactions are critical venues for language development and science learning, particularly for emergent multilingual students. Designing and facilitating such learning opportunities is pedagogically complex work and often requires significant shifts in practice. We report on a design study in which we partnered with 5th grade teachers to pilot inquiry-based science units designed for linguistically diverse classrooms. Through our analysis of classroom videos and teacher interviews, we surfaced ways teachers used the curriculum to create affordances for emergent multilingual students' language use and development, as well as tensions and recurrent "missed affordances" that emerged in their practice.