Human Digestion Demonstration – The Bread In The Bag

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!

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, 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?