Meatball has a serious thing for pine cones. I have piles of them all over my house. This pine cone experiment started when a question came up during a painting activity: why do pine cones open and close?
While painting with pine cones, Livia noticed that some of the cones that were shut tight had started to open, so of course we had to explore. I was surprised by how quickly this turned into a full-blown science experiment.
How to Do the Pine Cone Experiment
Pinecone Observation Science Experiment printable
Get the printableSeveral pine cones (open and closed)
3 clear glass bowls or containers
Warm water
Cold water
Fine motor tweezers (optional)
Set up three containers
Fill one container with warm water and one with cold water. Leave the third one empty and dry.
Observe and predict
Look closely at your pine cones. Are some open and some closed? Ask kids what they think will happen when the pine cones get wet. Livia guessed it had something to do with moisture since her paint was wet.
Add the pine cones to the water
Drop pine cones into the warm and cold water. The first thing my kids noticed was that they float! We tested whether open and closed cones both float (they do), and the round glass bowls worked like a magnifying glass for an up-close look.
Watch them close
Our wet pine cones started closing up fast, and the ones in cold water closed before the ones in warm water. Depending on the pine cone, closing all the way can take an hour or more, so check back.
Move them to the dry container
Once they close, move the pine cones to the dry container and watch them slowly open back up as they dry. It can take a day or two, and a sunny window speeds things up. Meatball loved being in charge of the transfers.
💡 Make it a sensory soup
My crew couldn’t resist turning the water into a pine cone sensory soup. Let them scoop, pour and transfer while they wait for the cones to close. It’s all part of the learning.
Why Do Pine Cones Open and Close?
Pine cones protect the seeds of the pine tree. When the air is dry, the scales open up so the seeds can fall out and blow away. When it’s wet, the scales close to keep the seeds safe until conditions are better for traveling.
So how does a pine cone move without muscles? Each scale is made of two layers of cells. When the scale gets wet, one layer swells more than the other, which bends the scale closed. As it dries, that layer shrinks again and the scale bends back open. That’s why even pine cones that have been off the tree for years still do it.
We pulled out some sponges to show how materials swell when they soak up water and shrink as they dry. (I was elbows deep in a water mess at that point, so no pictures of that part!)
With next to no setup and no big time commitment, this one was a hit. Next time we want to try different liquids.
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Turn this into a real science lesson at home or in the classroom with the printable observation and recording pages.
What’s included
- Experiment page with a hypothesis and prediction
- Pine cone observation sheet
- K-W-L chart
- Results sheet
- How to Use page that explains the science
- Instant PDF download, nothing is shipped
Perfect for
- Fall and winter science centers
- Preschool and kindergarten classrooms
- Homeschool nature study
- Outdoor learning
- Science journals
Pine Cone Experiment FAQ
To protect their seeds. Pine cones open in dry weather so seeds can fall out and blow away, and close in wet weather to keep the seeds safe.
Each scale has two layers of cells. When the scale gets wet, one layer swells more than the other, bending the scale closed. It opens again as it dries.
It varies by pine cone. Ours started closing quickly, but it can take an hour or more to close all the way.
Usually a day or two as it dries. Setting it in a sunny window or another warm, dry spot speeds it up.
Yes. The movement comes from the cells soaking up and losing water, not from the tree, so even old pine cones will open and close.
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Did you try it? Tell us how it went!
We love seeing these activities out in the wild: the lumpy letters, the snack breaks, the proud “I made a B!” moments. Leave a star rating, tell other parents what worked (and what totally didn’t), and add a photo of your setup if you’d like.
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This experiment was fascinating! Being a 74 year-old, with 48 years of teaching young children in public schools, I learned several important things about pinecones and how they behave! Thank you so much!
Thank you! I have been saving pine cones to create something with them! I learn something new today about open and close!
This is a fun idea but we definitely didn’t get immediate results after trying this several times. None of our pinecones in warm or cold water closed enough to see a noticeable difference until at least 30 minutes had passed.