Teaching a diverse group of students, including multi-age students can be quite challenging. One suggestion I have is for you to first determine the different skill levels and proficiency levels for the students. I am sure that you will find a wide range of proficiency levels and skills. Then, I suggest that you use peer mentoring/teaching, and pair up higher level students with the lower level students. I have found that peer tutoring really help both individuals and makes the learning that much more enjoyable for all involved. Also, I recommend that you include as many visuals in your teaching as you can, and have activities that incorporate all learning modalities- audio, visual and kinesthetic.