One of the Add-ons I feel will be useful for students is the Thesaurus. Teaching writing at the lower elementary level presents challenges as you teach word choice. Teachers try to steer students away from words like cool and great, but it has proven difficult to either use a book thesaurus or an online thesaurus. The new "Thesaurus Add-on" makes finding alternative words a breeze. Please see the screenshot below to see how it works.