Is Eating a "Waste" of Time?

I did a little project a couple of years ago on student misconceptions and the conceptual change model. I chose to do my lesson plan on digestion, specifically the fate of the food we eat. In my preliminary research, I found that many students have this idea that the food is eaten, goes through the digestive system, and emerges as waste from the anus (giggles all around). When asked about how much of the original food leaves the body, the numbers were extremely high - 50%, 90%, even 100%. This is quite understandable given our personal experience with said waste and no way of explaining the volume of it produced. Students have this abstract idea that food is needed for energy, but for all they know we somehow extract the energy (whatever that is) from food in the digestive system itself and then eliminate the food when we're finished "using it." Few students seemed to have any conception of how the food is used for growth, maintenance, repair of our own tissues/cells or what energy is. There are a lot of lessons suggested by these misconceptions, but at the time I was taking this class I was required to produce a single lesson plan that would address the misconception. I don't think it was very effective.

For my regents classes I wanted to start with the misconception, so the title of this post was my AIM. As a DO NOW I asked students to describe the fate of food from start to finish, expecting the misconception again to come out in their responses. They were however a little too saavy and mostly mentioned the part about breaking down food into smaller particles that were absorbed into the bloodstream and carried to the cells.

From the misconception, I planned a short project for students to do some cooperative group work, researching the structure and function of various parts of the disgestive system, jigsawing with other experts, then re-convening to put it all together into a coherent narrative. As part of the project, students will construct a scale model of the digestive system - schematically conceived - and use the model as a prop when they present. Each person in the group is responsible for detailing the fate of one nutrient - carbohydrate, protein, lipid. Here are the details:

A JOURNEY INTO THE DIGESTIVE SYSTEM & BEYOND

Your Task

1. Describe the fate of one nutrient in the human body:


a. A protein


b. A fat/lipid


c. A carbohydrate – starch


d. A carbohydrate – sugar.


e. A carbohydrate – fiber

2. Describe what happens if something goes wrong in the digestive system

--Describe real conditions that affect humans.

3. Create a scale model of the digestive system using everyday materials such as
cardboard, fabric, paper, etc.

Procedure:

1. Form groups of 4.

2. Each group member will become an expert in one of the following parts:


a. Mouth & Esophagus


b. Stomach


c. Small Intestine


d. Large Intestine & Accessory Organs (Liver, Pancreas)

3. Jigsaw: At different times, experts for each part of the system will get together to share notes. Then you will return to your main group. Since the different parts of the system work together, you will need to understand how all the parts work together. (See details)

4. Create a storyline detailing what happens to your nutrient. (See details)

5. Create a scale model of the digestive system. (See details)

Presentation:

Each group will have a 5-minute presentation. You will use the scale model as a prop to help you tell the story of your nutrient. (See rubric).

I will post some more of the details as we progress. Here are the original questions I've asked students to research:

Part 1: Basic Research (Use extra paper if needed)

• What does digestion mean?
• What is the basic structure and function of your organ/organs.
• What is the organ made of (what kinds of cells, tissues, etc)? What does the organ do?
• What do the specialized parts of the organ do?
• What does the food look like before it is worked on by your organ? After?
• What kinds of nutrients are digested by your organ/organs?
• What is the sequence of events within the whole digestive system? (Numbered list.)
• What happens if some part of your organ/organs malfunction? Explain, name a disorder.