This is an idea that I got from the other kindergarten teacher at my school (It also comes from those Letter Factory videos). When I talk about the vowels I discuss how they are the "glue" that holds words together. I've then point each of the vowels on a glue bottle and laminated them. Then I've put magnets on the back of each of them. When I'm spelling words on the board I bring the vowels (on the glue bottles) down and spell the words with them. We do this a lot when we're working with our word families. It's really helped my students.