Here are some suggested titles and themes you may want to consider for your series:
     Connections Themes: Some ideas for your series
     YA Novels for Adult ESOL Students
     Wordless Picture Books

The Connections book database enables teachers and facilitators to search for classic books. You can search by author, title, reading level, theme, and genre. For instance, if you click on themes, you can scroll to find one that is interesting to you. When you click on a theme, you'll see a list of books that are available.

     Book database