hungry caterpillar theme
Growing Caterpillar Science Experiment
easy STEM activity for kids
Looking for a simple, hands-on science experiment that will wow your little learners?
This Growing Caterpillar Science Experiment is the perfect mix of science, STEM, and storybook magic – inspired by The Very Hungry Caterpillar and just right for preschool, pre-K, and kindergarten classrooms.
With just a paper towel, markers, and a little water, kids will love watching their hungry little caterpillar “grow” right before their eyes!
It’s an easy science experiment for kids that introduces capillary action in a fun, visual way – and bonus points? It sneaks in fine motor skills, color recognition, and cause-and-effect thinking, too.
This activity is a total win for the classroom – but it’s also simple enough for parents to try at home!
Whether you’re teaching a caterpillar or butterfly theme, working on life cycles, or simply need an engaging spring science activity, this Growing Caterpillar Science Experiment is sure to be a hit with curious kids everywhere.
Before we jump into this fun science experiment, don't miss this...
If you’re planning a Hungry Caterpillar theme (or just have a class full of very hungry learners!), I have a free set of Hungry Caterpillar Sequencing Cards that pair perfectly with this activity.
They’re a simple, print-and-go way to practice sequencing, retelling, and story comprehension – all while building excitement for your caterpillar science experiment!
purpose
Screen-free fun
Demonstrates cause and effect
Fun book-extension activity
Teaches basic science concepts on capillary action
directions
How to do the Growing Caterpillar
Science Experiment for Kids
Tear off paper towels segments-one for every caterpillar you’d like to make
Color stripes onto the paper towel
Color the first stripe red
Color the remaining paper towel with green stripes
Tightly roll the paper towel around a pencil
Remove the paper towel caterpillar from the pencil
Place all your “caterpillars” on a tray
Set out a cup of water with a dropper
Add drops of water to the caterpillars
Watch as they GROW- just like the Hungry Caterpillar does in the book!
Continue adding water to caterpillars until they’re fully expanded
Discuss the science before you begin and again after you’re done (see the simple science explanation below)
And that is how a simple paper towel + a little water can turn into the coolest spring science experiment.
And if you’re planning even more Hungry Caterpillar fun, don’t forget to grab my free sequencing cards – they’re the perfect follow-up to this activity!
What's the Science Behind the
Growing Caterpillar Science Experiment?
So what’s really happening when your little paper towel caterpillar starts to grow and expand right before your eyes?
One of the best parts of the Growing Caterpillar Science Experiment (besides watching your students light up when their caterpillar starts to grow!) is that it introduces a real science concept kids will actually see in the world around them: capillary action.
This easy science experiment is a fun and visual way to explore capillary action — a big science term that simply means how liquid can move through tiny spaces, even against gravity.
When you add drops of water to your tightly rolled paper towel caterpillar, the water gets pulled into the dry paper towel fibers.
As more water soaks in, the paper towel starts to unroll and expand -making your caterpillar grow bigger and bigger!
It’s the same scientific principle that helps plants “drink” water through their roots and stems.
How Does This
Experiment Connect to the Real World?
This is how plants “drink” water! When you water a plant, the roots pull water up through the stem to the leaves and petals — just like the water traveled through your paper towel caterpillar. (This is also why celery or white carnations change color when you add food coloring to their water!)
Ever wonder why a paper towel soaks up a spill so quickly? That’s capillary action at work! The tiny fibers in the paper towel pull the liquid upward and outward — just like in this experiment.
Even super tall trees use capillary action to pull water all the way from their roots to their highest branches and leaves. (Pretty amazing, right?)
If you’ve ever raised caterpillars or butterflies, you may have seen them drink tiny drops of water — using their long tongue (proboscis) to pull liquid into their body, a little like capillary action on a teeny tiny scale!
This simple Growing Caterpillar Science Experiment might feel like magic to kids — but really, it’s the same science that helps plants grow, trees thrive, and even helps us clean up spills in the kitchen.
And that is how we turn a little spring science fun into a BIG real-world connection your kids won’t forget.
