This is not a formal presentation. Introduce this work as the child is reading or when the occasion arises.
As the child is reading or looking at words and he sees a word that he does not know, show the child the dictionary. Show the child how to look for words in a dictionary.
The child can also have a booklet of his own indexed like an address book to place words he happens upon that he may not know. The child writes words he doesn’t know and then reads them to familiarize himself with them.