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The Pumpkin Project — Math, Science, and Fun!

By Alycia Zimmerman on October 26, 2011
  • Grades: 3–5

Teaching in the upper elementary grades, I feel as if we sometimes have to sacrifice classic childhood experiences for academics. Building snowmen, rolling dough snakes, carving pumpkins . . . all things there’s no time for in our busy school day. Or is there? 

Always on the lookout for ways to work classic fun into the curriculum, I use our Pumpkin Project to teach estimation, measurement, place value, and other math concepts. The Pumpkin Project melds standards-based content with slimy, tactile teamwork, making it the perfect Halloween-free October (or November) activity. Here is how I teach this activity, complete with my data recording worksheets, extension ideas, and a video of my students in action as pumpkin investigators.

Some students become quite close with their pumpkins!


Step 1: Collecting Pumpkins

Here in NYC, cheery orange pumpkins start appearing at corner stores, flower stands, and in heaping piles at the farmers’ markets in early October. I think we make up for our lack of colorful foliage with an abundance of pumpkins. When I bring the first pumpkin in to school to set the stage for the project, I try to find an unusual one, misshapen or oddly colored.

When my students enter the classroom, they rush over to inspect the new “visitor” to our room. “What is this pumpkin doing here?” they all want to know. Gathering my students around the pumpkin, I explain that later on this month we will be doing an investigation using pumpkins. “What investigation?” they demand.

“You’ll have to wait and see. First we have to collect enough pumpkins for our investigation,” I say.

In general, I try to collect one pumpkin for every three to four students. This ratio allows all of the children to really get their hands into a pumpkin while preserving the group-work element. I ask parents to sign up to donate medium or large pumpkins, as well as disposable plastic tablecloths. You’ll also want to have a strainer, plastic bowls, and plenty of paper towels on hand for the project day.


Step 2: What Investigation?

Margaret McNamara has written the perfect book to introduce the pumpkin seed investigation. In How Many Seeds in a Pumpkin, Charlie’s class attempts to answer this very question. Charlie, the smallest child in class, also has the smallest pumpkin. To everyone’s great surprise, Charlie’s pumpkin has the most seeds — but I just spoiled the ending!

As you read the book, make sure to stop reading before you get to the page where the students share their pumpkin seed counts because your students will be doing their own pumpkin seed investigation. After their own experiment, you can compare their findings with the book. If you want to take a more open-ended approach, have your students pose their own questions for inquiry.


Step 3: Measuring Pumpkins and Making Predictions

Before “Pumpkin Seed Day,” I give each group a pumpkin and my students name them (some of the names are quite amusing). I introduce the difference between qualitative and quantitative observations. Then my students complete their qualitative data collection worksheet and quantitative data worksheet  with data about their pumpkins. With their data in hand, we discuss which type of data is more useful in predicting the number of seeds in the pumpkins.

A student closely observes the creases on his pumpkin.

For the quantitative data, my students experiment with how to best measure the circumference of their pumpkins. I provide measuring tapes, yarn, and rulers. To weigh the pumpkins, students stand on a scale holding their pumpkins, and then we subtract the students’ weights to determine the pumpkins’ weights. It is important to demonstrate how to count the creases on a pumpkin. Creases are the vertical lines on the pumpkin, and we count each crease from the “South Pole” to the “North Pole.” Students make a pen mark on the first crease they count so that they do not over-count the creases.

Each group transfers their quantitative data to a class chart, and we use this data to make predictions about which pumpkins will have the most seeds.


Step 4: The Pumpkin Project: Time to Get Messy!

Wear old clothes and an apron, and cover every possible surface in plastic tablecloths or cut-up garbage bags; this phase of the project is inevitably messy in the very best of ways! I cut open the top of the pumpkins before the students arrive. Students are instructed to lift the top off their pumpkin and separate the “guts” into two piles — pulp and seeds.


Step 5: Counting Time

After the students separate their seeds and rinse them in a colander, I clear away the pumpkins to a side table. Students then begin the challenging task of accurately counting their pumpkin seeds. (This can be done in a follow-up lesson if necessary.)

I ask each group to come up with a reasonable estimate without counting all of their seeds. Students have time to ponder how best to make their estimates. Some groups may choose to weigh their seeds, then weigh a subset, count the number of seeds in the subset, and then multiply by the appropriate ratio. Other groups may choose to divide the seeds up by volume and then count a smaller volume of seeds.

Each group must present their estimate and their method to the class before counting their total number of seeds. When counting the seeds, the students devise their own methods to keep track of the seeds they count. Some group their seeds, others record their running totals on paper. Finally, the students compare their total with their estimate and analyze the difference.

This project suggests so many math extensions — pumpkin seed arrays, word problems, graphing, and more. Don’t forget to return to the original investigation question. Were the students’ original predictions accurate? Why or why not? Which measurement was the best predictor of the number of seeds? You may want to finish reading aloud How Many Seeds in a Pumpkin and compare your students’ results with the results in the book.


Extensions, Read-Alouds, and Other Resources

For another approach to pumpkin math, check out former Classroom Solutions blogger Stacey Burt’s post “Pumpkin Pi.”  I loved her idea so much that I added a pi exploration to our pumpkin project this year. I had my students record the diameter and circumference of their pumpkins, as well as of various pie tins (in keeping with the theme.) Download my data collection worksheet.

We collected all of their data onto a class chart, and I asked my students what they noticed about the values. I probed, “About how many times the diameter is the circumference? Is this true for all of your measurements?” Together, my students discovered an important mathematical principle: the circumference of a circle is always about three times the diameter. Having reached this conclusion, I introduced the term pi.

Mathwire has some thought-provoking pumpkin math problems on their Web site including a pumpkin pattern problem and a pumpkin picking pdf!

For even more pumpkin lesson ideas, check out this Instructor magazine article. I particularly like the idea about growing mold in pumpkin “petri dishes."

I like to add some plant science to this unit by reading about how pumpkins grow. I love the poetic approach to the pumpkin life cycle in Pumpkin Circle: The Story of a Garden by George Levenson.

Please let me know if you try out this pumpkin project in your classroom, or if you have a different autumn activity you’d like to share with all of us. Happy autumn!

Comments (5)

Thank you for this lesson! Every year a farm donates pumpkins to our students, and I've always wanted to actually DO something with them. We are halfway through today, getting ready to dig out the insides! Wish us luck!!

WOW, that is so exciting to be hearing from you mid-project, Jake! I'm sure your students are loving it! We're doing our "pumpkin project" next week in my class. Since I have 32 students this year, we're going to open 10 pumpkins - it's going to be crazy! Good luck, have fun, and let me know how it works out!

Thank you so much for sharing. I am attempting my first PBL. Feeling reassured that I can do this. Thank youuuuu!

Thanks so much for the pumpkin ideas. We are going to try this fun stuff during our short week of school before fall break.

Thank you so much for sharing this idea!! I teach 7th grade Math and my students are going to love this. Thanks again :)

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