How do you handle L1 interference while keeping students engaged in a large class?

A discussion in Teaching English in Indonesia on the SpeakWise Indonesia teacher forum.

We've been thinking about the unique challenges we face as English teachers in Indonesia, especially when it comes to large class sizes and the influence of students’ first language. A teacher in our community recently shared how they navigate the delicate balance between maintaining fluency in English and understanding students' needs. This question matters because our approaches can significantly impact student engagement and learning outcomes. We’d love to hear your personal experiences and strategies — how do you effectively manage L1 interference while keeping your students motivated in a packed classroom?