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What does your family do with your jack-o-lanterns after Halloween is over? Most years we just throw them away. But last year we decided to do use our jack-o-lantern do some some Halloween science. An old jack-o-lantern was perfect for showing the kids the process of pumpkin decomposition. Decomposition, also known as rotting, is a process by which organic substances are broken down after death. Eventually, decomposition breaks organic matter down so that it becomes part of the soil again.
Note: You can find more Halloween activities on my Halloween Activities for Kids page.
So a few days after Halloween last year, we made the decision to NOT throw out our jack-o-lantern. Instead, we put our already-starting-to-rot pumpkin into an unused gardening box.
As you can see, even at the one week post-carving mark, the pumpkin was already starting to mold inside.
At the two week mark, the inside had turned black. Further, the pumpkin had started to shrivel and was beginning to collapse on itself.
And at the four week mark, it had shriveled up. By observing this process, the kids were getting a good sense for the process of pumpkin decomposition.
We actually let the pumpkin sit outside for several months. It eventually turned into a flat, hard item that was barely recognizable as a former jack-o-lantern. Sadly, I failed to get any pictures after the 4 week mark, and eventually one of the kids tossed it in the garbage. But we may just give this pumpkin decomposition experiment another go this year to see how it turns out.
If you plan to do this activity, you may also enjoy reading the book Pumpkin Jack
More pumpkin resources for kids
More pumpkin posts from Gift of Curiosity:
I love your science experiments! If I can convince hubby we may try it this year too! Thanks for the idea!
We did it this year with a piece of pumpkin I saved from making pumpkin cookies. It led to some interesting discussions with my 7 year old about cremation vs burial 🙂 Thanks for sharing with Afterschool!
Love this — funny because we do it without even trying. The kids notice every day at how our outdoor pumpkins are rotting… glad they’re getting some science learning in too 🙂 Thanks for sharing at After School!
I have done this with my kindergarten class for the last twelve years. Another variation that I do is putting a few slices of a pumpkin inside a glass jar for inside observation. Decomposition takes a little more time, however, it is fascinating to see what happens over time in a space that they can safely touch. If you choose to do it in a jar, make sure you use a glass jar so it doesn’t smell. Plastic jars tend to share the smell of the decomposition process. Also, to help the process, you need to open the container every week or few days to let air in. You may want to do it outside.
Allowing it to sit and rot is a great experiment! Featured you on Mom’s Library this week!
I used to teach at a school where a colleague would bury a jack o’ lantern, some newspaper and a foam cup. Later they would dig them up and have a talk about decomposition and its implications.
What a fun activity for kids! I wonder how a pumpkin would decompose in the ground compared to above the ground. It might be time to try a new experiment this year!
Hi Katie,
I have also done a journal where my 4K kiddos draw a picture in a “journal book” and then I write their words. It is a fun way to document what they are seeing over a period of time.
Missy
What a great idea to extend the learning!