What Happens When You Eat

Activity #1: How Long is the Digestive System
Have students cut a piece of yarn according to the following measurements.
Allow students to use different color yarn to represent different organs. After the yarn has been cut tie the pieces together.

Esophagus 25 cm
Stomach 20 cm
Small Intestine 700 cm
Large Intestine 150 cm
TOTAL 895 cm
Have students work out the percentages or ratios of the lengths of the different organs in the body in order to have a numerical idea of the differences along with the visual data provided by the string. Find out information (from books provided) about how much time food spends in each of these parts of the digestive system as well as which types of foods are broken down in each part.

Activity #2: Digestion
Place a sugar cube in a cup of water. Place about a spoonful of granulated
sugar in the other cup of water. Observe what happens.
Have students record the time it takes for each type of sugar to dissolve and work out the ratios of these

Activity #3: Carbohydrate Digestion
Have the students chew two unsalted soda crackers for two minutes without swallowing.
Students will be allowed to take check the solution every fifteen seconds and record the solvency of their saliva by counting the number of lumps present in a given amount at these 15-second intervals. Children will be instructed to plot the progression on a graph. Have them write a paragraph explaining the slope of the graph

Activity #4: Hands on Digestion
Place the hamburger, 3 eyedroppers full of 1M HCl, one tablespoon of Digestive Juice A and two tablespoons of Digestive Juice B into a plastic bag.
Knead the bad with your hands (simulates the stomach) for about 10-15 minutes, it will have been reduced to mainly liquid and have a definite odor.
have students write a summary of the activity, explaining the action of the hcl on the hamburger and noting any difference between the digested meat and the digested bread

Activity #5: How do Villi aid the Small Intestine in Absorption?
Compare how 1, 2, 3, and 4 folded paper towels absorb. Dip each paper towel into a cup of water (use the same amount of water in each cup). Record
the volume of water left in the cup (using a graduated cylinder).
Explain the comparison between the paper towels and the villi. How are these similar and how do they differ? What is the significance, if any, of the similarities and differences? Consider especially the mixture of water and stool and (thinking back to activity 1) describe what might happen if the food passed too fast or too slow through the large intestine.

Activity #6: A Digestive System Simulation
Procedure:
Things to make ahead of time:
1. FOOD TUBE: Lay out two parallel lines of tape on the floor, 3’apart and long enough for half the class to stand shoulder to shoulder on one side of the parallel
lines.
2. FOOD PARTICLE:
The food particle consists of M&M’s placed in small zip-lock bags. These are placed in wadded newspapers in small paper sacks. Place the small sacks in larger sacks with added newspaper. Place all sacks and add newspaper until the large plastic bag is full. This bag is then taped or tied closed to complete the food particle.

Action:
1. Peristaltic Movement: Put the food particle to be eaten at one end of the food tube and a large trash can at the other. Have students line up on both sides, facing each other, squeeze the food particle the length of the food tube.

2. Digestion: Label and/or instruct the players. As the food comes to a student they should narrate what they are doing and why.

Teeth – tear food apart (break plastic bag)
Saliva – use spray bottles to moisten food particle
Stomach – tear small bags apart
Pancreatic juices – spray food
Small Intestine – absorbs food, find bags of candy and pass to blood (the teacher can play the role of the blood)
Large Intestine – reabsorbs water, sponge up water on the floor
Rectum/Anus – puts the waste papers in the trash can

Draw a diagram of the digestive system, labeling its parts and correlating them to the props used in the experiment.