Chapter 8 Lesson 1 "How the Body Digests Food"

Materials:

• Workbook Activity on Digestion.
• Lesson 1 notes sheet "Optional"

Objective:

• Students will trace the path of food through the digestive system.
• Students will tell how and where digetive chemicals act on food.
• Students will describe what happens to undigested food.

Alaska Content Standards:

• SCI A-15 Students will use science to understand and describe the local environment.

Anticipatory Set: Teacher will read the Science Background "The Digestive System on P168 of the Teachers Edition. Then ask the students why the environment that food goes through in the different parts of thier digestive tract changes.

Recall the difinition of digestion from Chapter 1, "the process of breaking down food". Ask the students to answer the question, "where does digestion begin in the human body? Then take a cracker and begin eating it. Ask them if their answer has changed. What happened to the cracker in the mouth? (physically and chemically broken down.)

Teacher Input: Teacher will show a picture of the digestive tract, (168). Then the teacher will trace the path of the cracker through the digestive tract and explain what happens to it at each step of the way.

Teacher Modeling: Next the teacher will divide the digestive tract into its different parts. Show a picture of the mouth and explain the key parts of the mouth in digestion. From their discuss the esophagus and show a picture that represents peristalsis, define Peristalsis from this "Notes for 8-1" word document. Go back to the picture of the digestive tract and show the stomach. Tell what the stomach does and define Chyme.

While still showing the picture of the digestive tract show the students the area at the end of the stomach and the begining of the small intestine. Most scientists separate this into its own organ called the duodenum. This area is where bile that was stored in the gallbladder is added to the chyme. Define Bile and Gallbladder. Show the picture of the Gallbladder while doing the definitions. Show the picture of the stomach and how this bile can sometimes get back into the stomach and up the esophagus.

Return to the picture of the digestive system and show the next organ the small intestine. Explain what happens in the small intestine. Then show the picture of the small intestine with the villi on it. As well as the stand alone diagram of the villi. As the students what these little hairlike structures do. Make sure and read the "Did you Know" on P 170 at this point.

Show the digestive system picture again and mension the Appendix as you continue to trace the path from the small intestine to the large intestine. The large intestine is broken down into three sections based on the way it is positioned in the body. The large intestine mainly functions to take water out of the chyme then the waste is stored in the rectum. Show the picture of the rectum. Ask, "Why is it important that the rectum store waste. Why not just get rid of it as soon as it is created?"

Guided Practice/Check for Understanding: :

Show the students the ADAM information on the digestive tract and ask questions along the way to check for understanding.

Closure: How do doctors know so much about what is happening in the digestive system? Read the Achievements in Science on P 172.

Independent Practice: Students will complete the Digestion worksheet and the quiz on Chapter8, Lesson 1, "How the Body Digests Food"

Duration:

40 minutes + 10-15 for Independent Practice (Could be longer if taken for homework).