Central Idea Checkup

Key Details or Just Interesting Details? (Grades 4-5)

RI.4.2 / RI.5.2 Assessment

NC EOG Diagnostic Format

Student Name

Date

Nature’s Busy Engineers

1 Have you ever seen a animal that can change an entire landscape? Beavers are one of the only creatures on Earth, besides humans, that can do this. These large rodents are famous for their amazing building skills. Using their powerful, orange-colored teeth, they gnaw through tree trunks until the trees fall over. A beaver's teeth never stop growing, which is lucky because all that wood-chewing wears them down quickly!

2 Once the trees are down, beavers begin their main task: building a dam. They move logs, branches, and mud into a stream to block the flow of water. This creates a deep, still pond behind the dam. Inside this pond, the beavers build their home, called a lodge. The lodge has underwater entrances to keep the beavers safe from predators like wolves or bears. Beavers even have waterproof fur and webbed back feet that help them swim efficiently as they work.

3 While the dam is a great home for the beaver, it also helps the environment. The new pond creates a wetland, which is a special habitat for many other animals. Frogs, ducks, and fish move into the calm water. Plants that love water begin to grow along the edges. The pond also acts like a giant filter, cleaning the water as it moves downstream. By simply building their homes, beavers create a thriving neighborhood for hundreds of other species.

4 Because they have such a big impact on their surroundings, scientists call beavers a "keystone species." Just like the middle stone in an arch holds everything together, beavers hold their ecosystem together. Without these busy engineers, many wetlands would disappear, along with the animals that live there.

Assessment Questions

1. Which statement best describes the central idea of the entire passage?

A

Beavers have orange teeth that grow throughout their entire lives.

B

Beavers are skilled builders that create important habitats for many living things.

C

Beavers use mud and branches to build lodges with underwater entrances.

D

Beavers are known as "keystone species" because they are as strong as stone.

2. What is the main idea of paragraph 2?

A

Beavers use specific techniques and body features to build dams and safe homes.

B

Beaver lodges are very safe because they have hidden entrances under the water.

C

Wolves and bears are the main predators that try to hunt beavers in the woods.

D

A beaver's back feet are webbed to help it swim through the deep pond water.

3. According to the passage, which detail best supports the idea that beavers help the environment?

A

"These large rodents are famous for their amazing building skills."

B

"A beaver's teeth never stop growing... which is lucky because all that wood-chewing wears them down."

C

"The pond also acts like a giant filter, cleaning the water as it moves downstream."

D

"The lodge has underwater entrances to keep the beavers safe from predators."

4. In paragraph 1, the author mentions that beavers have "orange-colored teeth." Which of the following best describes this detail?

A

It is a key detail that supports the central idea of the entire passage.

B

It is the main idea of the first paragraph.

C

It is an interesting detail that describes the beaver's appearance but is not a central idea.

D

It is a detail that explains why beavers are called "keystone species."

5. Which of these would be the best summary of the passage?

A

Beavers have orange teeth and webbed feet. They use these tools to chop down trees and build houses in ponds. Many other animals live in these ponds too.

B

Beavers are rodents that build dams. These dams block streams and create ponds. Scientists call beavers "nature's engineers" because they work so hard.

C

By building dams and lodges, beavers physically change their environment. These changes create important wetland habitats that support many other species and keep water clean.

D

Scientists call beavers a "keystone species." This is because beavers are the only animals that can change a landscape. Without beavers, wolves and bears would have nothing to eat.

6. Based on the passage, why are beavers compared to a "keystone" in an arch?

A

Because beavers use heavy stones to build their dams.

B

Because their work is essential for the survival of the entire ecosystem.

C

Because they are as strong and hard to move as a large rock.

D

Because they build arches out of trees to protect their families.

Short Answer

The passage states that beavers are "nature's busy engineers." Identify two key details from the text that support this description.

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