Human Digestion Demonstration-The Bread in the Bag Demo

Human Digestion Demonstration – The Bread In The Bag. In the first post, I talked about a demonstration I use with my science class to show what digestion looks (and feels) like in the mouth. Click here to read Part 1. In this post, I will be talking about a digestion demonstration I use to show my students what digestion looks like in the rest of the digestive system.

The student reactions are even better than with Crackers and as I said before, when they’re done your course, they may forget many things but they will never forget the crackers & especially not the bread in the bag demonstration!

In this Post, I will cover Demonstration #2 – The Bread In The Bag

Demonstration #2 – The Bread In The Bag Materials: Ziplock bags, a large bottle of liquid (water or juice works well), a loaf of bread (you will need 1 piece per two-four students). This demonstration shows a) how your STOMACH works to break apart the bonds holding the bread together through chemical and mechanical digestion so that the nutrients can be absorbed b) how your LARGE INTESTINE recovers water and vitamins from the food and c) how your RECTUM stores the waste temporarily before it exits the body.

If you’d rather watch the demonstration outline, please see below.

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Procedure: 1) Take 1 piece of bread per two students. Rip in half so each student has ½ of a slice 2) Obtain a small sandwich bag from the front of the room

3) Tear your ½ slice of bread into smaller pieces and place it into your sandwich bag. What does this represent?

Food broken into smaller pieces by the Teeth

4) Your teacher will come around now and pour a small amount of juice into the bag.

Food submerged in the HCl of the Stomach – Chemical Digestion

5) Close your bag and squish the bread with your fingers until all of the pieces are really small. What does this represent?

Mechanical Digestion by the Stomach

6) Drain the liquid contents down the sink by creating a small gap which prevents the solids from escaping and compare it with an undrained sample. What stage of digestion does this represent?

If you are interested in a really engaging, hands-on and simply to use lab station activity to go along with your lesson, please CLICK HERE or the image below to learn more.

Water and Vitamins are reabsorbed by the Large Intestine

7) Put all of the contents of the bag into the garbage. What does this represent?

Waste is temporarily stored in the Rectum

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I have performed this demonstration many times and I’m telling you, the kids love it! They are totally grossed out, but they love it.

This activity, as well as others, are found within my Human Digestion Lesson which can be found HERE. If you enjoy the activity please check it out.

Click here to be directed to Part 1 of this post which explains a demonstration showing how the mouth aids in digestion.

Thanks.

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Comments

Minoo says

April 20, 2016 at 12:01 pm

Very well explained

- Fergy says
  
  May 28, 2018 at 9:08 pm
  
  Thanks
  
Sandra Mould says

May 27, 2018 at 9:48 pm

Hi, I love this! Just wanted to know what concentration of HCl you use?

- Fergy says
  
  May 28, 2018 at 9:08 pm
  
  Typically I just use OJ or sometimes even just water. HCl is too dangerous for what we’re doing and the chances that the kids will squish and break the bags is large enough that I don’t want to even try it. Also, It wastes a lot so I typically just use water.