Rewordify is a brand new tool that allows you to take any text and simplify the vocabulary while preserving the original text at the same time. You can paste a selection or an entire Web site into the text box and get an enhanced version that includes simplified language in parentheses by tier 3 vocabulary words.
There are some great teacher tools available, too. With a few clicks, generate print friendly vocabulary lists and quizzes from the text you select.
For more information, watch this tutorial: