Picture books without words offer a variety of activities for both ESL students and basic literacy learners who have children. Better yet, most of these books have such engaging stories that they are appropriate for learners with children at any age. Those learners in a class who do not have children would find them interesting as well.
For example, have ESL students look over a few pages in pairs or as a class to identify key characters and events. Review this vocabulary. Then have students tell part of the story in class. Try the same story again a lesson or two later, and transcribe the story into words as the student speaks. No need to correct students' grammar or vocabulary, but you can make a note and cover a common mistake in an upcoming lesson if you like. Come back to the same story a month or so later, transcribing the students' retelling. Compare the two and you will see an example of how your students have been improving their English. Of course, at any point encourage students to check out the book and "read" the story with their own children, either in English or in their native language.
Picture books without words are also the best way to help basic literacy learners (those who speak English fluently but do not read it well) begin reading to their young children. It addresses the concern, justified or not, of some students that they will read incorrectly to their children. Jointly look over the pictures and tell the story with your student first, and then encourage your student to check out one or two of these and read them to their children every day.