Probably the most fascinating science project on the life stages of a butterfly is actually watching a live egg or caterpillar transform into a butterfly. Search your backyard or a nearby park for large caterpillar eggs or caterpillars. Once they are located, put them into a container that allows air, but doesn't allow the caterpillars to get out. A jar with a cheesecloth top works well. Be sure to note which plant the caterpillar was on because that is its food. Provide plenty of food until the caterpillar begins its transformation into a chrysalis. At this point, all you can do is wait until the butterfly emerges.
If live butterflies cannot be kept in the classroom, keep them at home and write a scientific journal about the life stages you witness. Take photos or draw pictures of every stage, from caterpillar to butterfly. If the project does not begin with actual eggs, use books or the Internet to research that portion of the life cycle and include it in your journal. For a more creative twist, write a story about a certain butterfly. Give it a name, personality and a family and friends. Tell the story of a butterfly's life through the eyes of a butterfly.
Create a board game depicting the life cycle of a butterfly. Make pieces shaped like caterpillars to move around the board based on cards drawn on the players' turns. Once the player makes it to the end of the game, his piece will become a butterfly. Or create a quiz show game, having students answer questions regarding the stages of a butterfly's life to earn points.
Create a presentation board with photos or drawn pictures of the different stages of the butterfly's life laid out in a circular shape to show the cyclical nature of the process. Label each stage and describe what is happening to the butterfly. Go more high-tech and make a slide presentation on the computer. Start with one life stage on first slide, then add one stage per slide until the final slide shows the entire cycle. If you are crafty, form the butterfly's stages out of clay or fabric and showcase them in a shadow box. Be sure to label each stage and show them in their natural progression.