digestive system

physiology block for grade seven

still life by Paul Cezanne

This first week of Advent, I began teaching as a guest teacher the physiology block on the digestive system for grade seven at East Bay Waldorf in El Sobrante, CA. While the rhythm of the week included preparations for an Advent assembly, my grade seven students and I had a wonderful week learning about the journey of food through our bodies.

Here is a brief recap of our week:

Day One

I introduced the topic of digestion by bringing samples of food to the classroom - a good place to start! Food is valued by us as humans for several reasons. I cut an apple in half and showed the children the five-pointed core. From it, I created a drawing on the board to show the five "Apple Core Values of Food." At each point of the apple star, I worte: Combustion, Nutrtion, Tradition, Recreation, and Inspiration. Food is important to us because we use it for energy (combustion), for nutrients (nutrition), for culture and family (tradition), for social gatherings (recreation), and to inspire art such as in Cezanne's still life of fruit (inspiration). I said that the balance of these core values of food leads to happy, healthy lives.

I also posed an idea for them to think about: in going from origin to table, the less steps in food processing it takes, the healthier the food is. We compared an apple, a potato, a bag of trail mix, and a Lunchable. Just in attempting to read the ingredients on the Lunchable box was enough to convince us that some of those chemicals listed should not be ingested! We figured it took lots and lots of step to bring the Lunchable to the table. In contrast, the apple simply was planted from seed, grown, picked, washed, and eaten!

Day Two

The second day of the lesson we started with a discussion of how we engage our senses to start the process of digestion even before we take the first bite. Not only is this important physiologically, but it brings the whole human into the realm of the lesson (the core values of food also brings this holistic approach). Then I drew the anatomy of the human as I talked about the path of the food.

Day Three

On this day, I traced for children the path of the food using a schematic diagram of the digestive tract I drew on the board, and talked about what was happening to the food as it passed through the different parts. As a visual aid, I put some crushed crackers in a sandwich bag to show how the food looks in the mouth, then I added some water and flour to show how it looks as a bolus, then chyme, then took some water out to show undigested matter.

Day Four


For their main lesson book, I had them copy this table to show the functions of each part and organ. This tabular form helped to recap the lecture from the day before. The colored bars represent the five processes: motility, digestion, secretion, absorption, and elimination.

Day Five

On the last day, I emphasized some important points. I also brought the material back out of the parts to the larger picture of our place in the world. I commented that I believed how truly amazing it is to know that our bodies have been designed to perfectly break down the foods that are available to us from our earth. We are of this world, made of this world.