Many Internet sites offer butterfly kits that include not only the caterpillars, but also a feeder with food, a butterfly house (usually made of netting the children can see through, and even a mister to keep the air moist in the butterfly house. The caterpillars form cocoons and emerge as live butterflies. The butterfly house allows children to observe without handling the butterflies.
Caterpillars eat leaves. Children should place several stems with leaves on them in their butterfly house. Your kit should tell you what kind of leaves the caterpillars will eat. Avoid handling the caterpillars, because they are fragile. They also have hairs that contain substances that can irritate the skin. Keep the air slightly moist. This will help the caterpillars thrive.
It may be difficult for children to understand metamorphosis. Explain that the caterpillar will form a cocoon, change into a butterfly and emerge. Provide several stems in the butterfly house for caterpillars to suspend themselves from. They will begin to form their cocoons as they hang from these stems.
It will take several weeks for the butterflies to emerge. This provides an opportunity for teaching about metamorphosis. Children may have difficulty understanding that the caterpillar does not die; it changes form. At this point, do not discuss what happens to the caterpillar's body (it is absorbed and used for food); simply focus on the fact that this is a natural process where the caterpillar becomes a butterfly. It may be useful to get a book or film on tadpoles and show how they become frogs.
Ask students to name places where there are lots of leaves and stems where caterpillars could live. Explain that construction is taking away habitats for caterpillars. This can become a unit on establishing green areas in neighborhoods, and the children can even suggest locations for such areas.
As the butterflies begin to emerge, don't teach, just watch. Ask the children to describe what is happening. You may be surprised by their insights.
Now students can document what they have observed in writing. This process will allow them to internalize what they have observed. A graphic organizer that has three squares to write in can help students sequence their observations. Sequencing is a vital skill that is easily taught with a cocoon to butterfly project. Free graphic organizers are available online.
Students can draw or paint butterflies, as well as caterpillars and cocoons. A graphic organizer that gives them three squares to draw in can be useful. The drawing can be put in order from caterpillar to cocoon to butterfly, thus reinforcing the idea of sequencing.
After a few days, the butterflies should be released so they can adapt to the wild. This can be sad for some children, but explaining that the butterflies need to go make a home in the woods may help. If you have raised Monarch butterflies, you can use maps to show migrations, and this can become a lesson on migratory species. Monarch enthusiasts operate websites that offer students the chance to participate in Monarch tracking, as well as in creating Monarch habitats.