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Lesson Ideas

Teaching the Digestive System by “Making Poop” with Your Students

Are you looking for a fun way to cover the human digestive system in your elementary or middle school biology classroom? Try this hands-on activity suitable for kids of all ages.

Materials and preparation

  • Banana (½ per group)
  • Crackers (3-4 per group)
  • Lemon juice or clear vinegar (to represent stomach acid)
  • Water
  • Zip-lock plastic bag
  • 1 cut-off leg of tights/stockings (i.e. small intestine)
  • 1 plastic cup as a funnel (with cut-off bottom) 
  • 1 plastic cup as a plunger  
  • Gloves – small size (1 pair per student) 
  • Scissors 
  • A tray or large bowl
  • 1 paper cup with a hole (i.e. large intestine)
  • The following handout with instructions (edit depending on the students’ age)

Time requirement

You will have to adjust based on the class level. In most cases, you will need:

  • 10-15 min at the beginning of class to briefly go over (or review) the route the food takes.
  • 20-40 min for the hands-on activity (making the digestive system model). Older students will be able to follow the instructions in the handout themselves. Younger ones will need a lot of help.
  • 5-10 min to clean up.
  • 20-50 min for the reading assignment, which can also be done for homework.

Lesson plan

At the start of class, show this diagram of the human digestive system on the board.

Begin a discussion by showing the bananas and crackers and asking:

  • What happens when we eat our food? It goes into our mouth – then the stomach – intestines – and then we poop it out.
  • But it looks different when it comes out! It is mushy, mixed up, has a different color, and smells different. Where does this difference come from? All the healthy ingredients are gone. Where are they?
  • Somehow, we broke down the food and absorbed all the healthy ingredients. How did this happen?
  • Let’s make our own model of the digestive system and see what happens at each step along the way.

It’s a good idea to show the route the food takes through the digestive tract by tracing with your finger on the diagram on the board. Refer to it frequently during the hands-on activity to make sure the students know where along the way they are at each step.

This activity was developed based on other online lesson ideas found here.

Reading extension

This scientific article is a suitable follow-up assignment for middle school and lower high school students. It is a good occasion to discuss the gut microbiome and how to properly design a scientific experiment.

Can microbes make fruit flies stronger?

Check our website for even more microbiome-related scientific articles.

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