Synonyms are different words that have identical-or at least very similar-meanings. This set of activity sheets will introduce your students to using synonyms correctly. Activities include choosing similar words to replace selected words, identifying the correct words within a given list, identifying whether given pairs are synonyms or antonyms, and more. I find this worksheet section to be a paramount toward better writing skills. Having a solid vocabulary that you can call in at anytime starts with this, the simplest of tasks.
When you are looking for like words, it is helpful to also know their opposite meanings. That makes it a clear point indicator.