1. What information do teachers need to know about their learners to prepare good lessons? (e.g. age, nationality, etc.)

    Personally, I would say, the background of all the learners is the key information for teachers to prepare good lessons.  Such as educational background, interests in teaching, work experience (if they have), etc.

    2. Why is it important for teachers to know about their learners’ characteristics and needs? 

    Everyone is unique, they have diverse characteristics, backgrounds, and also different needs in taking this course. It would be helpful for teachers to get to know that earlier, then they could develop the syllabus step by step and adjust it in time. In my mind, it’s a win-win for both learners and teachers, because learners could have access to more specific and tailored course content that can meet their needs. At the same time, the teaching effect would be more efficient.

    3. How can teachers find out about their learners?

    I think teachers could get to know that by the following steps:self-introductions of learners, interactions through the course, questions and answers.