Students study digestion by observing what happens to a starch when it is combined with a chemical that models saliva. Students observe that iodine can pass through a membrane but starch cannot. They observe digestion of proteins, using meat tenderizer as an enzyme source. Students also model the absorption rate of villi in the small intestine.

Student Resources

• 3.1 Vocabulary
• 3.2 How Does Saliva Help Digestion?
• 3.3 What Happens When Starch Is Digested?
• 3.4 Can Starch or Iodine Move Through Plastic?
• 3.5 How Do Villi Absorb Liquid?
• 3.6 Organs of the Digestive System
• 3.7 Section 3 Assessment

Learn by Reading

For additional content-area reading, check out the Houghton Mifflin Science eBook: Grade 5, Unit A, page 36.