If I had a dime for every time my students misused then or than or their and there, I'd be able to retire in Hawaii! Alas.....this 12-week unit teaching common homonyms and homophones has helped cure the problem and I am not heading to Hawaii any time soon!! There are 12 worksheets using about 3-4 sets of these confusing words in sentences and then tests to go with the lessons. The kids have told me they love doing these because it is like playing detective to find the right word. I use this for 6-8th graders.