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Goo-ology: Digestion in a Bag

Activity Objectives

  • Students will be exposed to the major steps of digestion.

Vocabulary/Literature Resource

  • Digest, Chew, Swallow, Saliva, Stomach, Acid, Intestine, Elimination
  • Adapted from ESC’s Science Assembly Program

Materials Chart

Consumable supplies to gather and/or purchase   

  • Saltine Crackers
  • Baking Soda
  • Baggie
  • Water
  • Vinegar
  • Green Food coloring (optional)   
  • Sponge

Permanent supplies

  • Large tooth model (optional)
  • Scissors
  • Bucket

Activity Plan

Invite student volunteers to assist with each step of digestion.

  • Preparation: Mix ~ 1 sleeve of crackers with ~ 4 tablespoons of baking soda. Measure ~ ¼ cup of water, 1/3 cup of vinegar mixed with 2-3 drops of food coloring.
  • Student volunteer adds cracker/baking soda mixture to baggie, and uses either large tooth, or knuckles to simulate chewing. Discuss why chewing is important.
  • Student adds water (“saliva”). Mash crackers and water to coat thoroughly. Discuss the role of saliva.
  • Discuss swallowing. Student adds vinegar (“stomach acid”). Point out bubbles, discuss chemical reactions in the stomach. Mash crackers again to coat.
  • Student adds sponge, to demonstrate intestine absorbing nutrients and water. Cover sponge with cracker mixture, to absorb water. Discuss the small and large intestines.
  • Remove sponge. Remove air from bag, and roll into a tube. Student cuts off end of bag, and squeezes cracker mixture out into bucket. Discuss elimination.


This activity can also be modified to be an individual activity, with each student getting their own sandwich-size bag of crackers, and doing each step as a group.

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