RFC Levd SB 5/16/08 10:44 AM Page 3

RFC LevD SB 5/16/08 10:44 AM Page 3

How did the Olympic Games begin? ...... 4 What is the birthday of the United States of America? ...... 56 How do crocodiles clean their teeth?...... 6 How does gravity affect the tides?...... 58 What is the Statue of Liberty? ...... 8 Where do people pray to mountains? ....60 Why do leaves change color in the fall? ...... 10 What bugs us every 17 years?...... 62 Where did the ideas for our What can be learned from government come from? ...... 12 ancient graves? ...... 64 Why does a jumping bean jump?...... 14 Why did the dinosaurs die out? ...... 66 What is Earth Day?...... 16 What colorful art form began in America?...... 68 What is a mongoose? ...... 18 What happens underground ow do people know what time it is?.....20 H during winter?...... 70 What is the praying mantis?...... 22 How did Maggie and Lillian Rogers learn Who was Anne Frank? ...... 24 so much about the White House?...... 72 How is paper made? ...... 26 Why don’t people ride zebras? ...... 74 What was the Titanic?...... 28 Who holds the record for staying alive at sea the longest? ...... 76 What is the powder on a butterfly’s wings? ...... 30 Why do you look upside down in a spoon? ...... 78 Why is Mt. Rushmore famous? ...... 32 What is Carnegie Hall? ...... 80 What plant eats meat? ...... 34 What is ball lightning?...... 82 What was a victory garden? ...... 36 Who was Calbraith Rodgers? ...... 84 Where does chocolate come from?...... 38 Where did the first magnets What tea party became a part come from? ...... 86 of history? ...... 40 Why did the Spanish come Where does the trap-door spider live? ....42 to the Americas? ...... 88 What is recycling?...... 44 What animal makes bubbles What is a shooting star?...... 46 on leaves? ...... 90 Where was the first subway started?...... 48 What was so special about climbing Half Dome? ...... 92 Why is the lionfish left alone? ...... 50 What unique thing do bowerbirds do? ...94 How has the potato changed history? ....52 How do dolphins sleep without drowning? ...... 54 RFC LevD SB 6/23/06 1:22 PM Page 6

How do crocodiles clean their teeth?

1 If you saw a bird fly into the mouth of a crocodile, you would probably think that the crocodile was going to eat it. After all, most animals would not dare to enter the open jaws of a crocodile. However, the Egyptian plover, or crocodile bird, has a special relationship with the crocodile. This gentle bird acts as the crocodile’s personal dentist.

2 A crocodile obviously doesn’t brush its teeth or floss after meals. This means that the food that gets stuck in its teeth begins to rot. This can cause the crocodile some pain. To solve the problem, it opens its mouth wide to allow the plover to enter and clean its teeth.

3 Once inside the crocodile’s mouth, the plover feeds on the bits of meat lodged between the crocodile’s teeth. It also eats the tiny parasites that could make the crocodile sick over time. When the plover is finished eating, it flies out unharmed.

4 The cooperation between the plover and the crocodile helps both animals. The plover gets to enjoy an easy meal without worrying about being attacked. The crocodile gets a much-needed teeth cleaning. Both animals benefit from their unusual partnership and live longer, healthier lives.

6 Reading for Comprehension

Circle the correct answer for questions 1–5. Write your answer to question 6 on a separate piece of paper.

1. A crocodile gets its teeth clean by ______. A brushing them B opening its jaws to let in air C eating plants instead of meat D letting a bird eat the food between them

2. Which word in paragraph 1 means “connection”? A relationship B personal C special D dare

3. Which paragraph explains how the plover cleans the crocodile’s teeth? A 1 B 2 C 3 D 4

4. What happens when food between a crocodile’s teeth begins to rot? A It makes the crocodile feel pain. B It makes the crocodile hungry. C It makes the crocodile thirsty. D It makes the crocodile lazy.

5. You can conclude from the article that ______. A only the crocodile benefits from its relationship with the plover B only the plover benefits from its relationship with the crocodile C both the plover and the crocodile benefit from their relationship D neither the crocodile nor the plover benefits from their relationship

6. The animals you read about help each other. Think about a time when you helped someone. Tell what you did and how it was helpful.

Reading for Comprehension 7