Print out pictures of a pumpkin at each stage in the pumpkin life cycle. Provide students with a sheet of construction paper and challenge them to put the life cycle of a pumpkin in order, drawing arrows from one stage to the next. Instead of putting the cycle on one sheet of construction paper, students can place each picture on a separate sheet of paper and staple them in order to create a pumpkin life cycle book.
If you're teaching a unit on pumpkins during the fall, have students take a field trip to a local pumpkin patch and learn about the life cycle of a pumpkin firsthand. Many pumpkin patches have special school programs that allow students to tour the pumpkin patch and pick out a pumpkin of their own. Students can see the pumpkins still on the vine and in various stages of development at the green and orange pumpkin stages.
Fill a large plastic container with potting soil and pumpkin seeds. Have students take turns watering the pumpkin seeds daily and wait for the pumpkin to sprout. After a week or two, students will be able to experience the life cycle of the pumpkin by watching the seed sprout. Continue to let the pumpkin grow over time and continually remind students about the pumpkin cycle even after the lesson is over by having them check the progress of their pumpkin.
There are a variety of picture books dealing with pumpkins and the pumpkin life cycle that can help students better understand how a pumpkin grows. Some suggestions include "Pumpkin, Pumpkin" by Jeanne Titherington, "It's Pumpkin Time!" by Zoe Hall, "It's a Fruit, It's a Vegetable, It's a Pumpkin!" by Allan Fowler and "Patti's Pumpkin Patch" by Teri Sloat.
Cut open a pumpkin for students and let each student pick out a seed. Talk to students about the importance of the seed in the life cycle of the pumpkin. Place the seeds in a bowl of water and allow them to soak over night. The next day, help students open up the seeds to find the embryo inside.