xiii Unit 7 Human Development and Reproductive Health . . . . . . . . . . 546 Chapter 17 Human Development . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 548 Lesson 17.1 The Beginning of Life. . . . . . . . . . . . . . . . . 550 Lesson 17.2 Child Development . . . . . . . . . . . . . . . . . . . 556 Lesson 17.3 Adolescence and Puberty. . . . . . . . . . . . . 563 Lesson 17.4 Adulthood and Aging . . . . . . . . . . . . . . . . . 572 Chapter 17 Review and Assessment. . . . . . . . . . . . . . . 579 Chapter 18 Sexually Transmitted Infections and HIV/AIDS. . . . . 582 Lesson 18.1 Sexually Transmitted Infections (STIs) . . . . 584 Lesson 18.2 HIV/AIDS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 594 Chapter 18 Review and Assessment. . . . . . . . . . . . . . . 601 Unit 8 Human Sexuality. . . . . . . . . . . . . . . . . . . . . . . 604 Chapter 19 Understanding Sexuality. . . . . . . . . . . . . . . . . . . . . . . . . 606 Lesson 19.1 What Is Sexuality?. . . . . . . . . . . . . . . . . . . . 608 Lesson 19.2 Sexual Feelings and Behavior. . . . . . . . . . 618 Lesson 19.3 Unwanted Sexual Activity . . . . . . . . . . . . . 627 Chapter 19 Review and Assessment. . . . . . . . . . . . . . . 635 Chapter 20 Making Responsible Sexual Decisions. . . . . . . . . . . . 638 Lesson 20.1 Pregnancy Prevention. . . . . . . . . . . . . . . . 640 Lesson 20.2 Teen Pregnancy and Parenthood. . . . . . 653 Chapter 20 Review and Assessment. . . . . . . . . . . . . . . 659 Appendix. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 662 Glossary/Glosario. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 664 Index. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 695