Utah Agriculture in the Classroom

The Case of the Missing Pumpkin

Grade Level(s)

K - 2

Estimated Time

2 hours


Students will investigate the life cycle and decomposition of pumpkins.


Activity 1: 

Activity 2: 

Activity 3:

Essential Files (maps, charts, pictures, or documents)

Essential Links


bacteria: a group of single-celled living things that cannot be seen without a microscope that reproduce rapidly and sometimes cause diseases

decomposer: an organism that feeds on and breaks down dead plant or animal matter

decomposition: the breakdown of plant or animal matter, the process of decay

fungus: any one of a group of living things (such as molds, mushrooms, or yeasts) that often look like plants but have no flowers and that live on dead and decaying things

humus: a brown or black material in soil that is formed when plants and animals decay

nutrient: a substance that plants, animals, and people need to live and grow

phenomenon: an observable event which is not man-made; plural form is phenomena

pumpkin: a large, rounded fruit with a thick rind, edible flesh, and many seeds

Did you know? (Ag Facts)

Background - Agricultural Connections

The pumpkin is one of only a few foods native to North America that is still eaten today. Native Americans used pumpkins for food and medicine. Dried pumpkin shells served as bowls or containers for storing grains and seeds. Flattened strips of pumpkin were dried and made into mats.

Pumpkins were a main part of the Pilgrims' daily diet. If left uncut and stored in a cool, dry place, pumpkins can keep for several months. Colonists made pumpkin pies by slicing off pumpkin tops, removing the seeds, filling the pumpkin with milk, spices, and honey, and then baking it all in hot ashes.

Today, the majority of pumpkins grown are sold for decorating and carving. The tradition of carving pumpkins at Halloween started with the Irish. The original jack-o-lanterns were made from turnips. When the Irish immigrated to the US, they found that pumpkins were in large supply and were much easier to carve.

The pumpkin is a member of the cucurbit family which includes gourds, squash, cucumbers, and melons. Pumpkins come in a variety of shapes, sizes, and colors. Most pumpkins are orange, but they can also be yellow, red, white, gray, or pale green. Pumpkins range in size from less than a pound to over 2,000 pounds.

A pumpkin is a fruit that grows on a vine. They are typically planted in late spring or early summer for an October harvest. After a pumpkin seed sprouts, large leaves begin to grow on vines. Eventually, the vine blooms with yellow flowers. Following pollination, the female flower begins to grow a small green pumpkin that will turn orange as it continues to grow. When the vines turn brown, the pumpkins are ready to harvest.

Pumpkins left in the field will be eaten by animals or they will decompose. The phenomenon of decomposition is a natural process through which nutrients are recycled back into the soil. Insects, fungus, and bacteria are decomposers that eat the dead tissue from the pumpkin and excrete it in a form that helps live plants grow.

In nature, dead plants and animals decompose and become humus. Humus acts like a sponge to help soil hold water. It also traps air in the soil and provides nutrients. Plants need air, water, light, and nutrients to grow. When farmers plant crops in the soil, the growing crops take out nutrients. The farmers can replace those nutrients by tilling decomposing plants back into the soil. The surviving seeds left by a decomposing pumpkin have the ability to sprout and grow into a new pumpkin plant, continuing the pumpkin life cycle.


Interest Approach – Engagement

  1. Ask the students if they have ever carved a pumpkin into a Jack-o-lantern.
  2. Have the students predict what they think would happen to a Jack-o-lantern if they kept it until the next summer.
  3. Read the book Sophie's Squash by Pat Zietler Miller. Discuss with the students what happened to Sophie's squash. Could that happen to a pumpkin?


Activity 1: Decomposing Pumpkin

  1. Read the book Pumpkin Jack by Will Hubbell. Use information from the book and the Background Agricultural Connections section of this lesson to discuss the phenomenon of decomposition.
  2. Tell the students that they are going to have the opportunity to observe the decomposition of a pumpkin. Show the students the aquarium or "decomposition tank." Explain to the students that the decomposition tank needs fresh soil from nature that contains decomposers (insects, fungus, and bacteria). Take them outside to collect soil from an area on or near the school, or obtain compost from a local nursery. Collect enough soil to fill 3-4 inches of the aquarium.
  3. Ask the students how they will measure the observable changes that will occur in their pumpkin. Have the students record the characteristics of the pumpkin before it is placed in the decomposition tank. Students can draw a picture of the pumpkin and record the date, size, shape, and color of the pumpkin in their Pumpkin Science Journals.
  4. Place the pumpkin into the soil so that it is partially buried. Moisten the contents of the aquarium with a spray bottle to simulate rain and cover the tank with several layers of plastic cling wrap. Tape the edges with packing tape.
  5. Each week the students will record observations in their journals. Instruct them to make note of any significant changes, such as mold growth or a pumpkin seed that begins to sprout. Have the students work in small groups to interpret the results of their observations and draw conclusions about the decomposition process.
  6. As the investigation draws to a close, brainstorm ways the decomposition process could be sped up or slowed down. As an extension activity, students can design their own investigations, such as comparing the decomposition rate of different organic substances or observing how the decomposition process is affected by altering the variables of temperature, light, or water.

Activity 2: Pumpkin Planters

  1. Provide each student with a mini pumpkin or place students in groups with one larger pumpkin per group. Tell the students that you
    are curious to know if a pumpkin can grow inside of a pumpkin. Conduct a class poll to determine how many students predict yes and how many predict no. Invite students from both sides to share why they answered yes or no.
  2. Ask the students, "What is needed to grow a pumpkin?" (a pumpkin seed, light, the proper temperature, air, and water) "Where do pumpkin seeds come from?" (a pumpkin)
  3. Have the students use garden trowels or spoons to fill their pumpkins with potting soil. Water the soil and place the pumpkins in a sunny spot. Ask the students if their pumpkin seeds have what is needed to sprout and grow into a pumpkin plant.
  4. Each day, have the students observe their pumpkin plants and record observations in their Pumpkin Science Journals.

Activity 3: The Great Pumpkin

  1. Read the book Life Cycle of a Pumpkin by Ron Fridell and Patricia Walsh or Pumpkins by Ken Robbins.
  2. Use the students' experiences of sprouting a pumpkin seed and investigating a decomposing pumpkin (in Activities 1 and 2) to discuss the life cycle of a pumpkin plant. Include the following points in the discussion. First, the seed is planted. From the seed a plant sprouts, growing leaves and then flowers. From the flowers, small green pumpkins form. When the pumpkins are ripe, they turn orange and can be harvested. Inside of the ripe pumpkin are many seeds which can be planted to start the cycle again. Pumpkins left in the field will decompose leaving seeds that can sprout and grow into a new pumpkin plant the following year, continuing the pumpkin's life cycle.
  3. Provide each student with the art items listed in the Activity 3 Materials List. Explain to the students that they will be creating a model of the pumpkin's life cycle.
  4. Have each student draw a Jack-o-lantern face with a black marker or crayon on the back of one of the paper plates. Color the rest of the plate and the back of the second plate orange.
  5. Trace the paper patterns onto the construction paper using the appropriate colors. Another option is to copy the pattern directly onto the construction paper. Cut the shapes out and punch a hole in the top of each one.
  6. Thread the yarn through the holes of the seed, leaf, flower, green pumpkin, and
    orange pumpkin in the correct order of their formation on the pumpkin plant. Tie a simple knot at the top of each plant part.
  7. Staple the end of the yarn closest to the orange pumpkin shape to the front of the plate without the face. 
  8. Staple the paper plates together around the edges with the orange sides facing out. Leave a gap on one side of the pumpkin to pull the seed, leaf, flower, and growing pumpkins out with the piece of yarn. Slide the string of plant parts into the center of the Jack-o-lantern.
  9. The students can practice describing the life cycle of the pumpkin by slowly pulling the seed, leaf, flower, and growing pumpkins from the Jack-o-lantern.

Concept Elaboration and Evaluation

After conducting these activities, review and summarize the following key concepts:

We welcome your feedback! Please take a minute to tell us how to make this lesson better or to give us a few gold stars!


Enriching Activities

Suggested Companion Resources


Adapted with permission from a lesson plan originally developed by Oklahoma Agriculture in the Classroom.

Decomposing Pumpkin photo used with permission from Kevin Krejci.

Activity 3 adapted from an activity originally developed by Rose Judd-Murray.


Lynn Wallin & Pat Thompson

Organization Affiliation

National Center for Agricultural Literacy