The letter B is so much fun to teach. After all, there are tons of fun things to associate with it: balls, bubbles, balloons (which we didn't do), bouncing, bears, butterflies!
I found a fantastic idea here for making a chrysalis. In a nutshell, you paper mache a balloon with tissue paper and then insert a butterfly inside for your demonstration.
Mine wasn't nearly as neat as the tutorial's but it worked for the purpose and the kids got a kick out of it. My 3-year old's been playing with it ever since!
I suppose that I should preface this with the note that we read Lois Ehlert's Waiting for Wings.
While I'm not a huge fan of her earlier works, I love love LOVE this book and several others with this style of artwork: Eating the Alphabet, The Leaf Man. And after reading the book, we reviewed the life cycle of a butterfly -- hence the chrysalis . . .
And this very lovely caterpillar that I made out of a nice stretchy, fuzzy sock and pipe cleaners. You have to love those last minute lightbulbs!
I should, of course, have included Eric Carle's The Very Hungry Caterpillar but if I don't think about it before preschool/playgroup starts, I certainly don't think of it during the process! Oh well, most kids have read that book anyway and I'm sure that they'll have the opportunity to see it again! It still turned out well.