I found this great website called WordSift. What you do is copy a text that relates to your lesson you are teaching. You paste it into the text book and click Sift. As a result, it enlarges words that were used mostly in the text and keep words that were not used as much smaller.
Another feature: it gives you Google images and videos for, at first, words that were found a lot in the text. You can also choose the word from the list at the top.
Another feature: you can choose one of the words and it will give you a visual dictionary.
A great feature: it gives you the sentences from the text that uses the word you chose to highlight. This is an awesome feature because you can go through the sentences and discuss with the students context clues or different ways the word is used.