Students can do this every few days, creating a bar graph of the caterpillars' growth. Invite older students to use rulers to measure the caterpillars' growth daily and record their data in a notebook. Students can determine the average daily growth rate of their caterpillars. They may also make a line graph noting any growth spurts or plateaus. Keep daily diaries.
Students can keep daily journals, describing in words and pictures the caterpillars' changes.
Once the caterpillars have become chrysalises, invite students to make a sketch in their journals of what they think the butterfly will look like, then make another sketch when the butterfly emerges. After the butterflies have emerged, move them to an aquarium to observe for a day or two before releasing them. Place a wet sponge in a dish so they have water to drink. Invite an entomologist to visit the class and demonstrate how to collect and tag butterflies for tracking purposes. Have students examine prepared slides of butterflies under a microscope.