This is an example of how living things grow and develop. The caterpillar goes into a cocoon then comes out and has turned into a butterfly. The caterpillar turns into something different than it was before and it is doing different functions.
To go with our study of birds, and chickens in particular, I set up a Chicken Life Cycle project. I like to do life cycle work on paper plates.the circular layout reinforces the cyclical nature of a life cycle better.