1. Table of Contents
Birds
The Physics of Flight
Mammals

2. Characteristics of Birds
The bodies of most birds have adaptations for flight.

3. Characteristics of Birds
Air sacs and a four-chambered heart help birds obtain oxygen and move it to their cells.

4. Characteristics of Birds
Birds have four-chambered hearts and double-loop circulatory systems that efficiently move oxygen to their cells.

5. Characteristics of Birds
Some birds like this hawk have a crop and a gizzard. The crop stores food, and the gizzard crushes food.

6. Adaptations for Flight
- Birds
Previewing Visuals
When you preview, you look ahead at the material to be read. Preview Figure 1. Then write two questions you have about the diagram in a graphic organizer like the one below. As you read, answer your questions.
Adaptations for Flight
Q. How are birds adapted for flight?
A. They have lightweight bones, wings, and contour feathers.
Q. What is the function of contour feathers?
A. They give shape to the body and help the bird balance and steer during flight.

7. End of Section: Birds

8. Staying in the Air - The Physics of Flight
The difference in pressure above and below the wings as a bird moves through the air produces an upward force, called lift, that causes the bird to rise.

9. Relating Cause and Effect
- The Physics of Flight
Relating Cause and Effect
A cause makes something happen. An effect is what happens. As you read, identify the physical properties of a bird’s wing that cause lift. Write them down in a graphic organizer like the one below.
Cause
Air flows around the wing.
Effect
The shape of the wing causes a difference in air pressure that produces an upward force.
Lift
Contour feathers give the wings a smooth shape.

10. More on Bird Adaptations
- The Physics of Flight
More on Bird Adaptations
Click the PHSchool.com button for an activity about bird adaptations.

11. End of Section: The Physics of Flight

12. Mammal Diversity - Mammals
This circle graph shows the percentages of species of some groups of mammals.

13. Mammal Diversity - Mammals Reading Graphs:
What percentage of species are bats?
21.8 %

14. Mammal Diversity - Mammals Calculating:
What percentage of species are not bats?
78.2 %

15. Mammal Diversity - Mammals Graphing:
Suppose you used the data shown in the circle graph to make a bar graph. Which bar would be tallest?
The group with the greatest number of species, rodents, would be the tallest.

16. Mammal Diversity - Mammals Predicting:
What total should all the percentages in the pie chart add up to? Do you have to add the percentages to obtain your answer? Explain.
100; no, you do not have to add them because it is a circle chart—the entire chart stands for 100 percent of the items counted— in this case, mammal species.

17. Building Vocabulary - Mammals
A definition states the meaning of a word or phrase by telling about its most important feature or function. After you read the section, reread the paragraphs that contain definitions of Key Terms. Use all the information you have learned to write a definition of each Key Term in your own words.
Key Terms:
Examples:
monotreme
marsupial
gestation period
Key Terms:
Examples:
placental mammal
placenta
Key Terms:
Examples:
mammal
Egg-laying mammals are called monotremes.
The yak is a member of the group of vertebrates called mammals.
Unlike a monotreme or a marsupial, a placental mammal develops insides its mother’s body until its body systems can function independently.
Marsupials are mammals whose young are born at an early stage of development and usually continue to develop in a pouch on their mother’s body.
mammary gland
Every young mammal is fed with milk produced by organs in its mother’s body. These organs are called mammary glands.
The name of this group comes from the placenta, an organ in pregnant female mammals that passes materials between the mother and the developing embryo.
Marsupials have a very short gestation period, the length of time between fertilization and birth.
diaphragm
Mammals breathe in and out because of the combined action of rib muscles and a large muscle called the diaphragm.

18. Click the SciLinks button for links on mammals.

19. Data Sharing Lab - Mammals
Click the PHSchool.com button for an activity about sharing data for the Consumer Lab Keeping Warm.

20. End of Section: Mammals

21. Graphic Organizer Characteristic Monotremes Marsupials
Placental Mammals
Born live, crawl into mother’s pouch
How Young Begin Life
Hatch from egg
Born live
Milk from pores or slits on mother’s skin
Milk produced by mother in her pouch
Milk produced by mother
How Young Are Fed
Spiny anteater or duck-billed platypus
Human, giraffe, bear, rabbit, whale, etc.
Koala, kangaroo, or opossum
Example

22. End of Section: Graphic Organizer