One of the best tools I use for vocabulary development when teaching English as a second language are picture books. This includes older children!
Picture books, like all books, enrich vocabulary. More than television or listening to speech. One reason is that books are more likely to have an opportunity for higher language. (I expanded more on this here.)
Additionally, books, especially books for young children are repetitive. For example a plot line (albeit, a rather dull one) might be: "Who is throwing? Dog Is throwing. Who is throwing? Cat is throwing." The animals, syntax and -ing verb of throwing is repeating and easily learnt.
Moreover, it is easy for students to glean clues from the pictures. An unknown word can be puzzled out from the picture. This is true even of books for slightly older children.
Next week I'll explain how to use picture books to teach English as a second language to older children.