1. Unit 3 Lesson 4 How Do Animals Reproduce? Copyright © Houghton Mifflin Harcourt Publishing Company

2. Unit 3 Lesson 4 How Do Animals Reproduce? Life in Full Circle Copyright © Houghton Mifflin Harcourt Publishing Company Fish lay eggs.

3. Unit 3 Lesson 4 How Do Animals Reproduce? Life in Full Circle Copyright © Houghton Mifflin Harcourt Publishing Company birds lay the eggs. Bird parents protect the eggs until they have hatched.

4. Unit 3 Lesson 4 How Do Animals Reproduce? Bringing Up Baby Copyright © Houghton Mifflin Harcourt Publishing Company Some animals, such as turtles, are on their own as soon as they hatch from their eggs.

5. Unit 3 Lesson 4 How Do Animals Reproduce? Bringing Up Baby Copyright © Houghton Mifflin Harcourt Publishing Company Other animals, such as penguins, give their young a great deal of care. Penguins keep their young warm and fed until they are strong enough to take care of themselves.

6. Unit 3 Lesson 4 How Do Animals Reproduce? Bringing Up Baby Copyright © Houghton Mifflin Harcourt Publishing Company Animals such as deer, bears, rabbits, cats, and kangaroos take care of their young by feeding them milk. These animals care for their young for months or years until the young can live on their own.

7. Unit 3 Lesson 4 How Do Animals Reproduce? Growing Up Copyright © Houghton Mifflin Harcourt Publishing Company

8. Unit 3 Lesson 4 How Do Animals Reproduce? Growing Up Copyright © Houghton Mifflin Harcourt Publishing Company Just like other animals, humans go through stages of development. It takes many years for a human baby to grow into an adult. After a human egg is fertilized, it grows inside the mother. After nine months, the baby is born. When babies are born, they have no teeth. They are not able to walk on their own. Babies grow into toddlers. Toddlers learn how to walk and how to speak.

10. Insect Life Cycles Copyright © Houghton Mifflin Harcourt Publishing Company Most insects undergo metamorphosis as they develop into adults.

11. Unit 3 Lesson 4 How Do Animals Reproduce? My, How You’ve Changed! Copyright © Houghton Mifflin Harcourt Publishing Company In complete metamorphosis, an animal goes through four different stages in its life cycle. An egg hatches into a larva. A larva develops into a pupa. A pupa develops into an adult.

12. Unit 3 Lesson 4 How Do Animals Reproduce? My, How You’ve Changed! Copyright © Houghton Mifflin Harcourt Publishing Company A butterfly goes through complete metamorphosis. The larva of a butterlfy is called a caterpillar. The caterpillar grows into a pupa. Inside a chrysalis, the pupa becomes an adult butterfly.

13. Unit 3 Lesson 4 How Do Animals Reproduce? My, How You’ve Changed! Copyright © Houghton Mifflin Harcourt Publishing Company What are the stages in a butterfly’s life cycle?

16. Unit 3 Lesson 4 How Do Animals Reproduce? My, How You’ve Changed! Copyright © Houghton Mifflin Harcourt Publishing Company Some insects, such as dragonfiles and termites, go through a different series of changes. In incomplete metamorphosis, an animal goes through three different stages in its life cycle. First, the animal hatches from an egg as a nymph. Nymphs look like tiny adults without wings.

17. Unit 3 Lesson 4 How Do Animals Reproduce? My, How You’ve Changed! Copyright © Houghton Mifflin Harcourt Publishing Company As the nymph grows larger, it molts. Molting happens when an insect sheds its hard outer skeleton. After several moltings, the insect, which now has wings, reaches its adult stage.

18. Unit 3 Lesson 4 How Do Animals Reproduce? My, How You’ve Changed! Copyright © Houghton Mifflin Harcourt Publishing Company What are the stages in the life cycle of a grasshopper?