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This lesson plan for grade four, from the Food for Thought nutrition curriculum, teaches students about the digestion process and the organs of the digestive system.

Learning outcomes

Students will gain an understanding of the digestive system and the way the human body processes food.

Teacher planning


Handouts and transparencies

Digestion diagram
Make into an overhead transparency. Provided by Nutrition Services Branch of the North Carolina Division of Public Health and published in the Food for Thought curriculum.
Open as PDF (38 KB, 1 page)
Chewing your chow
Provided by Nutrition Services Branch of the North Carolina Division of Public Health and published in the Food for Thought curriculum.
Open as PDF (26 KB, 2 pages)
The Saliva Solution
Provided by Nutrition Services Branch of the North Carolina Division of Public Health and published in the Food for Thought curriculum.
Open as PDF (16 KB, 2 pages)


  • Unsalted saltine crackers (one per student)
  • Apples (enough for each student to have half of an apple)
  • Pitcher of ice water
  • Small paper cups (one per student)
  • Orange
  • Panty hose leg (narrowest part)
  • Two large sheets of paper
  • Tape measure
  • String (at least fifty feet in length)
  • Glue

Teacher background

The following background information about the digestion process comes from Esther Weiner’s book The Incredible Human Body: Great projects and activities that teach about the major body systems

Digestion process
Document by Esther Weiner
Open as PDF (12 KB, 1 page)


Like most mammals, humans have different types of teeth for biting and chewing. Ask students if all their teeth look the same. Ask how the front teeth differ from the back teeth. Front teeth (incisors) are sharper and bigger, back teeth (molars) are flat and broad. While food is broken down somewhat by chewing and grinding, most digestion takes place by body chemicals. Chemicals known as enzymes break down food in the mouth, stomach, and small intestines.


Digestion begins in the mouth. As teeth crush and grind the food, an enzyme in saliva begins breaking down the starches into sugar. Ask the students what happened when they put the saltine in their mouth at the beginning of class. Look at the label on the package. Saltines are made from flour and have little or no sugar. Explain to students that the sweet taste means an enzyme in their saliva had started to break down the starch to sugar. This is one of the first steps in digestion. Starches are broken down into sugars.


After food leaves the mouth it goes down the esophagus. Show the students where the esophagus is on the overhead. Demonstrate swallowing by place the orange at the top of the stocking. Use your hands to move the orange down the tube. Muscle waves along the esophagus help squeeze the bolus of food to the stomach. This process is called peristalsis. Your esophagus muscles take seven seconds to push a ball of food from your throat to your stomach.

Stomach and intestines

After the food leaves the esophagus it goes into the stomach. Strong muscles in the elastic stomach squeeze and mash the food to break it down. Digestives juices made of chemicals and enzymes also help break down proteins in the food. The food then enters into the small intestines to be broken down further by digestive enzymes from the liver, pancreas and gallbladder. After the food is digested into small particles, it moves from the digestive tract into the body. The nutrients from the food pass into the blood and are carried to every cell in the body where they will be used to build new cells, repair old ones and provide the body with energy. That is why it is important to eat healthy foods to build and repair all the parts of our body. Undigested materials such as fiber and water continue into the large intestines. The large intestines absorb the water turning it into a paste which is excreted through the anus.


  1. Give each student a small piece of cracker and tell the students to take a small bite. Ask them not to chew or swallow the cracker, just hold it in their mouths. Ask the following questions:
    1. What happened to the cracker when it was in your mouth?
    2. Why did it start to get softer?
    3. What did you taste?
    4. Wait a few minutes, then ask: Has the taste has changed? Did it become sweet?
    5. Did the cracker get soft in your mouth even if you were not chewing?
  2. Using the teacher background information above, explain the digestive process and the role of the digestive system. Note: consider presenting the material one section at a time as outlined in the resource and doing the corresponding practice and assessment activity before moving to the next section.
  3. Teeth: Distribute the “Chewing Your Chow” handout and provide each student with half of an apple. The handout asks students about the chewing process and which teeth they used when eating the apple. As a class, do the activities and instruct students to record their responses.
  4. Saliva: Distribute and direct students to complete “The Saliva Solution” handout. Students will answer questions about how the saltine cracker is broken down from starch to sugar with saliva. Discuss answers with students.
  5. Swallowing: Give each student a cup of ice-cold water. Instruct them to drink and feel the cold water travel down the esophagus. Place the orange at the top of the pantyhose and use your hands to move it through to demonstrate how food moves through the esophagus.
  6. Stomach and intestines: Ask for two or more volunteers. Trace the students’ bodies onto large sheets of paper. Using the “Digestive Diagram” teacher resource as a reference, direct students to work in teams to draw and label parts of the digestive system into their life-sized silhouettes. The digestive tract is more than twenty-five feet long in a child who is four feet tall. Using a tape measure, instruct students to measure two twenty-five foot lengths of string. Direct them to fit and glue the “digestive tract” into their drawings.


An assessment may be done from the students’ completed handouts. They should be able to respond to verbal questions about the digestive process.

  • North Carolina Essential Standards
    • Healthful Living (2010)
      • Grade 5

        • 5.PCH.4 Understand body systems and organs, functions, and their care. 5.PCH.4.2 Summarize the functions of the organs which make up the digestive system. 5.PCH.4.3 Interpret the relationship between and among the vessels and organs of the circulatory system....

North Carolina curriculum alignment

Healthful Living Education (2006)

Grade 4

  • Goal 4: The learner will apply knowledge and behavior self management skills to areas of nutrition and physical activity for healthy growth, development, and maintenance.
    • Objective 4.01: Identify the major components of the digestive system and summarize the digestion process.