I am beginning to work on sight words with my 5yo. If you don't know what sight words are, you can go to Kid Zone and read more about them. There is also a list of what words you need to focus on for each grade.
When my 8yo was in Kindergarten, I got sick of using flash cards to teach the sigh words. It was boring. and he did not seem to retain many of the words. He still struggled with very common words like; the, did, out, etc.
I decided to make a worksheet for him using the Dolch list for Kindergarten. I used boxes to help show where the letters go. I also used free clip art where I could to help show the word. Finally, I put it in a sentence. He got one sight word to focus on per week and every day he copied it once. It worked out great for him.