The Life Cycle of Butterflies is a four- to six-week unit designed and tested for 2nd graders that highlights the life cycle of the Painted Lady butterfly (Vanessa cardui). This butterfly is especially well suited for classroom study. It is small and brightly colored, will accept a variety of foods, is found worldwide, and undergoes complete metamorphosis in a relatively short time (from three to four weeks, depending on the temperature).

The main objective of the unit is to introduce young children to the concept of life cycles by using one organism as an example. Students also learn observational and recording skills, and add to their scientific vocabulary.

The first eight lessons focus on caterpillar and chrysalis stages of the Painted Lady butterfly. Students begin their study of these two stages by sharing their prior knowledge of caterpillars and then, as a pre-assessment exercise, they draw what they think a caterpillar looks like. In Lesson 2, they learn about caterpillars’ basic needs for air, water, food, and shelter and make and record their first observations.

In Lessons 3 through 6, emphasis is placed on developing observational and recording skills. Students watch the caterpillars as they crawl, hang upside down, spin silk, eat and eliminate waste (frass), rest, and shed skin (molt).

In Lessons 7 and 8, the caterpillar signals the end of this stage of its life cycle by hanging upside down from the top of its shelter in a distinctive J-shape. It molts one last time and is transformed into a shining chrysalis. Students observe and draw the chrysalis and speculate on what is happening to their caterpillars.

Lessons 9, 10, 11, and 12 focus on the adult stage of the life cycle, the beautiful butterfly. As the butterfly emerges, students observe the process and identify the butterfly body parts and learn how they function. For the next few days, students provide a variety of food for the butterflies and observe the specialized sucking mouth, the proboscis, in action. Then, after several days, the children release the butterflies, with the realization that butterflies are part of the natural world.

In the final three lessons, students refine their understanding of the butterfly as an insect and of the life-cycle concept. First, they review their own data and observations of the life cycle of the Painted Lady. Then they relate to other living things what they have learned about butterflies.

The Appendices contain important information, including post-unit assessments of student progress, read-aloud stories about the discovery and history of silk, information on how to construct free or low-cost butterfly flight cages, and information about raising a second generation of butterflies. Also included is an annotated bibliography of books that contains references for teachers and students, examples of children’s literature, and general sources of information about life cycles.