Skip to Content

Outdoor STEM: How Long are Your Small Intestines?

Use this super fun & easy outdoor science activity to show kids just how long their small intestines are and learn a little about the human body too!

This activity gets a few bonus points from us!  First, it’s a STEM activity (a little science, a little math) and it can be done outside (let’s face it — all of our kids could use a few more minutes outdoors, right?!)

AND — a big one — it involves a little gross human body science that’s sure to impress your kids 🙂

Don’t know what it is but kids like gross. 

So grab the items you’ll need (I’m sure you have them in the house) and join us outside for some science-y fun!


Outdoor STEM: How Long are Your Small Intestines?

If you have kids or teach kids, you know they ask a LOT of questions about their body. 

Sometimes very relevant questions —

“Where does the food go when I eat it?”

and sometimes very gross questions —

“Why do we poop?”

Questions — or in science terms, inquiry — is how we all learn about things so it’s actually awesome that they are asking them!  And today’s science activity will give your child an inside look at their body.


Human Body Experiment: Digestive System & the Small Intestines

There are a lot of activities and experiments about the digestive system (and we’ll share some of the great resources we found below) but what really grabbed our interest was when we read some details on the small intestines.

Did you know that an adult’s small intestines are about 23 – 25 feet long?!  The length will vary for males & females and also by your age.  And for a child, their intestines would measure about 20 feet long. 

Your small intestines are also about one inch in diameter — just about the diameter of a garden hose (how convenient is that! 🙂

So we decided to head outside, grab a hose and really see just how long our intestines would be if they were all stretched out.

For the activity, you’ll need the following:

  • a garden hose (or two if you have one shorter than 25 feet)
  • a ruler to measure the diameter of the hose
  • and a tape measure — I suggest using one that has a safety lock on it like the Powerlock 25-Foot Measuring Tape since you’ll be measuring a long distance.  Try this kid-friendly measuring tape (affiliate links) for younger kids if you don’t have one at home as they are really great to have around for math activities like this one!


The first thing we did was use the ruler to measure the diameter of the hose just to be sure we had one that was about an inch in diameter. 

And then we got to work measuring out 23 feet of garden hose — go with whichever length is stated in the book or video resource you choose to use (see our list below). 

First, stretch out the garden hose so it’s straight and can easily be measured.

Then begin at one end of hose and place the end of the tape measure down and hold it tight!  Now have your kids take the tape measure and stretch it out to 23 feet.  You can see we used a Powerlock 25-Foot Measuring Tape but if you have one that’s shorter, just measure as far as you can, mark your spot and then continue on until you have the 23 feet marked out.

And now comes the fun part!

You now have your small intestines all measured — 23 feet of a 1-inch diameter hose 🙂  So have your child pick it all up and scrunch it in front of their stomach.


 Because all of this …


 … is suppose to neatly fit in there!

We folded and scrunched but it was still a lot of ‘hose’ — and it was a great visual activity!

Now we all know that our intestines are much more flexible than a garden hose and collapse really well — but that’s still quite a bit of ‘organ’ in a small place 🙂


Learning Resources for the Digestive System

To learn more about how the small intestines work and play a part in digestion for the body, we recommend the following resources which include affiliate links so you can learn more about each:

We really like the UnCover the Human Body book (which can be hard to find but so worth it if you do!) Another great alternative is the SmartLab Squishy Human Body — both give kids an inside look at the organs of the body!

Another great resource is the Educational Trivia Card Game – Professor Noggin’s Human Body.  These can be used by body system (each card is clearly labeled) or for an overall look at the various body systems — fun to use at home or in a classroom.

We love using books and videos from the Magic School Bus series!  They have both picture books and chapter books so kids can grow with the series.  For this activity, I would recommend The Magic School Bus Inside the Human Body for younger kids if you’re looking for an overview of the body with just a few facts about the small intestines. They also have a great video series: The Magic School Bus: Human Body DVD

For older kids, try Bill Nye The Science Guy: Digestion DVD.  

And all ages will learn quite a bit from Magic School Bus Presents: The Human Body: A Nonfiction Companion to the Original Magic School Bus Series



The Science of Sound Waves & How We Hear

Fingerprint Science for Kids

Exploring the 5 Senses