A grammar lesson for homophones with an initial focus on the differences between there, their and they're. Could easily be adapted/extended with homophones that your class are struggling with. I have done this lesson as individual tasks and paired/group work, and as both a quick brush-up lesson or a lesson that takes the full period. It's flexible to work however you want it to depending on the needs of your class.
It ends with a teamwork activity as a 'reward' for the earlier activities.