Do your students get these words mixed up? Mine always do at the beginning of the year so I created this practice set.
There is one page of notes that I begin with. It's in color but prints nicely in grayscale too. It includes explanations of each of the three words, example sentences, and a few other notes.
There are 8 practice exercises, each being half a page with ten sentences the students will fill in the blank with the correct form of the homophone. Two of each practice exercise are on the same page so it's ready for you to toss one in the copier and save some paper.
Then there are two tests. Each has 20 sentences the same style as the practice pages.
All the practice exercises and tests have keys.
The way I use this is that I teach with the notes, guide them through the first exercise as much as needed. The second, third, and fourth ones are independent with me going over one a day. Then I give test one. Students who achieve a mastery-level score are compacted out and don't have to complete #5-8 practices or test #2 the next week. Sometimes I put the students who have mastered it together to write a story using the three words many times and they can work on that during the time each day that the rest of us are still going over their, they're, and there.