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Read and discuss “The Excretory System.”
Guide students to complete the activity for creating a Human Body Book that
includes a title for each diagram (RM 1:
Digestive System and
RM 2:
Excretory
System), description of the function of each system, and labeled and colored
organs as specified in the student edition.
Book entries will continue for the next
several lessons.
Explain
Pages 195–198
Physical and Chemical Changes
Physical changes occur when a substance has a change in one of its physical
properties, such as density, size,
smell, or luster.
Physical changes do not alter
the chemical makeup of the substance.
Examples of a physical change include
tearing paper, adding food color to water, or chewing food to break it into smaller
pieces.
If a substance has a change in its chemical properties, a chemical change
occurs.
New substances form
during a chemical change.
Examples of a
chemical change include paper burning, organic material decomposing, and
vinegar reacting with baking soda.
Photosynthesis is an example of a chemical
change that occurs in plants.
Physical and chemical changes occur during
digestion in humans.
The Digestive System
Our cells need energy and nutrients from food to survive and grow.
Food that we
eat must be broken down into molecules that can be used by
our cells.
Large
molecules of carbohydrates, proteins, and fat are broken into even smaller
molecules during digestion.
Lesson 1: Physical and Chemical Changes in Digestion
Unit 5:
Structure and Function of Organisms, Part 2
