I love the word mittens so much I wrote my own story about a little boy and his mittens. One day I may post. I did this project with 2.5 year olds and five year olds. I change the difficulty by adding steps. The 4 to 5 year olds were asked to pick one mitten and to copy the colors and pattern on a white mitten.
I read The Mitten by Alvin Tresselt... an awesome book and my favorite version. Also, a great project to do with scraps of fabric and yarn.