pathfinder edition
NGPathfinder.org
TEACHER’S GUIDE
October 2011
Engage Students
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Article Preview and Prior Knowledge
page 2
Before students preview the entire article, have them read the headline and study the photos of the spiders on the cover and on pages 2-3. Ask: What do you think of when you think of spiders? Invite students to share if they have an emotional reaction to spiders. Have students share what they already know about spiders, including their size, shape, and color, where they are found, and what they eat. Prompt students to tell if they think spiders are good or bad for our planet. Then have students page through the article to preview the images and read the captions. Be sure to point out the sidebar on page 5.
page 3
Overview
Spiders!
Introduce Vocabulary
Summary
In this article, students explore the world of spiders, an animal found almost everywhere on Earth. More than 40,000 kinds of spiders live on our planet. Spiders have different ways of stalking and trapping their prey, which include insects, other spiders, and even frogs and birds. Students learn about the types of silk spiders make and their hunting styles. Spiders play a beneficial role in nature by eating many insects that are pests and cause crop damage.
Learning Objectives
As students read this article, they will: • understand that organisms have structural and behavioral adaptations that help them survive; • classify animals into major groups according to physical and behavioral characteristics;
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List the Wordwise words on the interactive whiteboard or any board and ask the class which words they already know, which words they think they know, and which words they don’t know. Discuss the words and student interpretations. Then read the definitions with the class.
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Introduce the Comprehension Strategy Main Idea and Details Explain that the main
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idea of a paragraph or of a section is the most important idea. Point out that sometimes the heading in an article gives important clues about the main idea. Sometimes one sentence gives the main idea of a paragraph or section. Other times, readers need to read the entire paragraph or section and ask themselves what is most important. Tell students that supporting details give more information about the main idea.
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Project the “Spider Supper” section of the article on page 4 from the digital edition and highlight it. Have a student read the subhead and the first sentence in this section. Ask: What do these tell you about this section’s main idea? (It will be about what bolas spiders eat.) What supporting details might you look for? (examples of what they eat and how they eat)
• understand that animals perceive and respond to information about their environment; • identify main ideas and details to aid comprehension.
Wordwise arachnid: an animal with eight legs and a body divided into two parts (page 5) exoskeleton: an animal’s hard outside covering, such as a shell (page 5)
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Tell students that as they read, they should look for the main idea of each paragraph and the details that support it. Model this frequently throughout this article, marking specific points with a sticky note in the digital edition.
predator: an animal that kills and eats other animals (page 4) prey: an animal eaten by other animals (page 4)
National Geographic Explorer, Pathfinder
Page T1
October 2011
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Explore the Article
page 4
page 5
Read and Discuss the Science
page 6
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Before students read pages 4-5, have them study the diagram of the spider’s body parts on pages 4-5 and the chart on page 5. Then invite them to read the article’s introduction. Tell students that as they read, they should look for the main idea in the section (see Comprehension activity). Read the sections “Spider Supper” and “Looking for Prey” with students. Point out that predators often have specialized structures and behaviors that help them catch their preferred prey. Lead a discussion about the role the bolas spider’s behavior plays in the spider’s survival. (Bolas spiders prefer to eat moths. So they put out a scent that attracts these flying insects. Then they spin a strand of silk topped with a sticky bulb, which they use to snag prey.) Then lead a discussion about how spiders use their senses to hunt prey. Reinforce how spiders eat by having students retell the sequence in their own words. Then have students read the “Family Ties” section. Use the chart on page 5 to discuss the differences between arachnids and insects.
Build Comprehension
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Point out to students that in the introduction on page 4, the phrase, “to begin her hunt for food,” is the main idea. One way to know this is to look at the supporting details, which tell what the spider does to catch the moth. Use the digital edition to highlight the main idea in one color and its supporting details in another.
Support Struggling Readers Call attention to the subhead “Family Ties.” Explain that the expression family ties means people (or animals) that are related to each other and probably share some characteristics.
National Geographic Explorer, Pathfinder
Read and Discuss the Science
page 7
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Before students read, have them examine the photos on pages 6 and 7 and read the captions. Then read the sections “Woven Wonder” and “Made to Order” with students. Be sure that students understand that while all spiders make silk, not all silk is the same. Discuss the different kinds of silk and their different uses. (sticky and stretchy for webs, stiff for egg sacs, dry to line nests, and dragline to support webs or ballooning) Ask students to imagine ballooning and to describe what this ability lets a spider do. (to quickly move from place to place) Have students read “Building a Web.” Ask: What determines the shape of each type of web? (how the spider hunts) Zoom in on the photo of the orb web in the digital edition and have students describe how it is made. (It has spokes like a bicycle wheel; frame draglines; and sticky, elastic threads that spiral into the center.) Ask: How does an orb web catch prey for the spider? (Insects crash into it and become tangled up. Spiders sense movement in the web and rush to eat the prey.) Have students read “Funnels and Nets.” Ask them to describe the different types of webs mentioned in this section. Explain that the different webs are designed to help spiders hunt in different ways (see Comprehension activity). Display and discuss the poster. Then, have students list the unique behaviors of the different spiders mentioned in the “Building a Web” and “Funnels and Nets” sections and on the poster.
Build Comprehension
Have students review the photos on pages 6 and 7. Ask: What is common about these photos? (They show spiders and their webs.) Tell students that photos can tell the main idea of a section. If all the photos show a similar idea, that idea is likely the main idea. Have students use the photos to state the main idea of pages 6-7. (Spiders use silk to make different kinds of webs.) Page T2
October 2011
eExtend Science Learning
Explore the Article
page 8
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Divide students into groups. Have each group make a list of the spiders mentioned in the article and on the poster, their body parts, and their behaviors. Then have students make a poster that shows the different spiders according to criteria of their choice, such as sizes, environments, behaviors, and prey, and share their poster with the class. After all groups have shared their posters, discuss the criteria each group chose to focus on and how well the selected spiders fit within each category.
page 9
Read and Discuss the Science
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Before students read pages 8-9, have them review the photos and read the captions. You might zoom in on each photo in the digital edition to show additional details. Have students share what they think about or feel when they hear the word tarantula. Then invite students to read “Without Webs” and “Knock, Knock.” Say: These sections focus on the spiders’ use of silk for hunting. They also describe other behaviors in which spiders perceive and respond to information in their environment. Give examples by asking: Why do jumping spiders use a safety line? Why would trapdoor spiders put silk hinges on their trapdoors? Why would a tarantula use a trip wire instead of keeping watch for prey out in the open? (These behaviors help them catch prey from a distance, keeping the spiders safe.) Then read the section “Predator As Prey.” Explain that the difference between being a predator and being prey often depends upon the other animals in the ecosystem. Have students discuss the behavior of the pirate spider and how it takes advantage of other spiders. Remind them that not all spiders make webs, but most use silk in some way to catch prey. Have students read the final section “Living with Spiders.” Ask: What important role do spiders play in keeping the balance of life on Earth? Remind students that all living things have a role in keeping balance in an ecosystem.
Build Comprehension
As students read page 9, have them share how tracking the main ideas throughout the article helped them understand the information in the section “Living with Spiders.” Encourage students to use supporting details from the article to explain how spiders help balance life on Earth.
National Geographic Explorer, Pathfinder
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Alternatively, use the Explorer website (ngpathfinder.org) to have students play the game “What do you know about spiders?”
Evaluate Have students complete the blackline master while they read. Or have groups work together to complete it after reading. Use their responses to evaluate their understanding of the content and vocabulary. Have students share their responses, and address any misconceptions. When students have finished reading, review the learning objectives listed on page T1. Share the objectives with students and have them do a self-evaluation of their learning.
Fast Facts • Spiders don’t usually bite people and do so only if they perceive an attack. While all spiders have venom, only about 25 of the 40,000 types of spider can cause serious injury to people. • Spiders range in size. Some are small enough to fit on the head of a pin. Others are large enough cover a dinner plate. • People in some cultures eat spiders. Cooked spiders taste nutty and sticky like peanut butter. • Spider silk is the strongest known natural thread. Scientists think spider silk could be used for many purposes, such as a possible material for bulletproof vests. • Scientists have found several chemicals in spider venom that may help to treat some diseases, such as Alzheimer’s Disease and some types of cancer.
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Spiders!
Name:
Before Reading hoose the best Match Words to fill in the blanks in the Wordwise Chart. For example, consider how C tuna and shark relate to each other. Which best fits on the A line under predator and which on the A line under prey? Complete the Wordwise Chart with the remaining match words.
Wordwise Chart
predator
prey
A B
A B insect
arachnid C D
C D
Match Words
A
tuna shark
B
bird worm
C
butterfly spider
D
8 legs 6 legs
During Reading As you read, use this chart to write about what you learn about how each kind of spider uses silk to catch prey.
How it uses silk Copyright Š 2011 National Geographic Learning. Teachers may copy this page to distribute to their students.
Spider
National Geographic Explorer, Pathfinder
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October 2011
Spiders!
Name:
After Reading Answer the following questions. Then find the answer words in this Word Search. Shade the words with your pencil to finish the outline of a spider.
1. A spider’s body consists of two main parts: the upper part and the _________________, or lower part. 2. An exoskeleton is a hard outer _____________________ that protects a spider’s body. 3. Unlike insects, spiders can have up to eight individual ___________________. 4. Tarantulas spin a tripwire that trips unsuspecting ___________________. 5. Some spiders reach new ___________________ by ballooning on draglines. 6. Spiders produce silk from fingerlike ___________________ called spinnerets. 7. Spiders inject poison into their prey from their _____________. 8. An orb spider’s web has sticky, elastic _____________ that spiral into the center. 9. Pirate spiders are predators that hunt other _________________. 10. The limbs on a spider’s jaw that help hold prey while the spider injects poison are called _________________. Spider Find Word Search D I E C N I I K O I B O J C N I V S G R F
I P P N D F F U S C D H H S O H B O E O D
K F L D O E D B I G O G D O I B S Y I I G
W D J A F N Y E R N M S F I F D U T T F O
Y G N J C D G E C D E D S H D S Y V Y H J
R V D G G E N W S F N V P S H F F Y W R D
National Geographic Explorer, Pathfinder
L B S H H C S I H I F G O D G G B B F E S
P A P A L P S U N O I K G G C I C E L W F
H F S B K U E G D S P L F H N O X R D G G
P W F A N G S H S G U J G V S V V S Q J K
H S K C V D S A F H G B H S O U B T C K G
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G C H S G P H O T V T H V G D A I Y G V D
D G N V I S G U H S H X S H F T O V K H S
L B G D S U B I V S R Z O R H S S D D B F
B O E F U E D N D D E C I B I C G H T W G
J R K B S N D H F O A G P K G V N U E E O
S F J H D O A P O I D V G U P S E I D L I
T Y W I K B S T H P S X Z H J R J O Y G L
Copyright © 2011 National Geographic Learning. Teachers may copy this page to distribute to their students.
J O S H S O V S C S A S K N G O G R Y W P
October 2011
Spiders! ANSWERS Before Reading 1. C hoose the best Match Words to fill in the blanks in the Wordwise Chart. For example, consider how tuna and shark relate to each other. Which best fits on the A line under predator and which on the A line under prey? Complete the Wordwise Chart with the remaining match words.
Wordwise Chart
predator
prey
shark
A B
tuna
A B
bird
worm
insect
arachnid spider
C D
butterfly
C D
8 legs
6 legs
Match Words
A
tuna shark
B
bird worm
C
butterfly spider
D
8 legs 6 legs
During Reading As you read, use this chart to write about what you learn about how each kind of spider uses silk to catch prey.
How it uses silk
Spider bolas
spins silk with a sticky blob; swings it to hit moth
orb weaver
spins a web that looks like a bicycle wheel
funnel
spins web that looks like a tunnel
sheet
spins sheet web that hangs between grass blades
net-caster
spins small web; throws web at a passing insect
jumping
spins dragline to get it to safety if it misses prey
water
spins silk ball that protects it under water
trapdoor
digs a burrow in the dirt; spins silk trapdoor
tarantula
spins silk trip lines
pirate
invades web of another spider; tugs on threads
National Geographic Explorer, Pathfinder
Page T6
October 2011
Spiders! ANSWERS After Reading Answer the following questions. Then find the answer words in this Word Search. Shade the words with your pencil to create the outline of a spider.
abdomen 1. A spider’s body consists of two main parts: the upper part and the _________________, or lower part. shell 2. An exoskeleton is a hard outer _____________________ that protects a spider’s body. legs 3. Unlike insects, spiders can have up to eight individual ___________________. prey 4. Tarantulas spin a tripwire that trips unsuspecting ___________________. places 5. Some spiders reach new ___________________ by ballooning on draglines. tubes 6. Spiders produce silk from fingerlike ___________________ called spinnerets. fangs 7. Spiders inject poison into their prey from their _____________. threads that spiral into the center. 8. An orb spider’s web has sticky, elastic _____________ spiders 9. Pirate spiders are predators that hunt other _________________. 10. The limbs on a spider’s jaw that help hold prey while the spider injects poison are called palps _________________. Spider Find Word Search J O S H S O V S C S A S K N G O G R Y W P
D I E C N I I K O I B O J C N I V S G R F
I P P N D F F U S C D H H S O H B O E O D
K F L D O E D B I G O G D O I B S Y I I G
W D J A F N Y E R N M S F I F D U T T F O
Y G N J C D G E C D E D S H D S Y V Y H J
R V D G G E N W S F N V P S H F F Y W R D
National Geographic Explorer, Pathfinder
L B S H H C S I H I F G O D G G B B F E S
P A P A L P S U N O I K G G C I C E L W F
H F S B K U E G D S P L F H N O X R D G G
P W F A N G S H S G U J G V S V V S Q J K
H S K C V D S A F H G B H S O U B T C K G
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G C H S G P H O T V T H V G D A I Y G V D
D G N V I S G U H S H X S H F T O V K H S
L B G D S U B I V S R Z O R H S S D D B F
B O E F U E D N D D E C I B I C G H T W G
J R K B S N D H F O A G P K G V N U E E O
S F J H D O A P O I D V G U P S E I D L I
T Y W I K B S T H P S X Z H J R J O Y G L
October 2011
Engage Students
page 10
Article Preview and Prior Knowledge
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Before students preview the entire article, have them read the headline and deck and study the photo of the cactus on pages 10-11. Ask: What are deserts like? Invite students to share what they know about a desert environment. Have them page through the article to preview the images and read the captions on pages 12-15. Then, have students discuss their first impressions about the land and animals shown in the illustrations. Ask: How do you think these animals survive?
page 11
Overview
Introduce Vocabulary
Center of Life Summary
In the dry, scorching desert, the saguaro cactus is the center of life. It can live for more than 150 years, grow upwards of 12 to 18 meters (40 to 60 feet) tall, and provide food, shelter, and water to wide variety of animals. The saguaro thrives because of adaptations that it uses to trap, store, and turn scarce water into food and energy, creating a successful habitat in a harsh ecosystem.
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Project Wordwise on page 15 of the digital edition on your interactive whiteboard or any white wall to preview the vocabulary words. Read aloud the words and definitions with the class. Then highlight the word parts in each word (adapt / ation; eco / system; habit / at; photo / synthesis) and have students share what they know about each word part. Have students complete the paragraph in the Before Reading section of the blackline master, writing the vocabulary words on the spaces provided.
Introduce the Comprehension Strategy
Learning Objectives
Summarize Tell students that to summarize, readers tell
As students read this article, they will: • describe and understand structures in plants and their functions, including the life process of photosynthesis; • understand that living things in an ecosystem are interdependent; • understand that organisms have adaptations that allow them to survive in a certain environment;
the most important ideas and the important supporting details. Explain that when readers summarize the main ideas of each section in an article, it helps them understand the entire article. They look for the important things in an article and put together these main ideas to create an article summary.
• understand that plants make their own food and are the base of most food chains;
National Geographic Connection
• summarize to aid comprehension.
Join National Geographic and the National Park Service for a 24-hour race to count species living in Saguaro National Park in the Sonoran Desert. Classrooms can join the BioBlitz through a “virtual field trip.” Check out http://www.nationalgeographic.com/ bioblitz for more details.
Wordwise adaptation: a behavior or body part that helps a plant or animal survive (page 13) ecosystem: all the living and nonliving things in an area (page 13) habitat: a place where a plant or animal lives (page 15) photosynthesis: the process by which plants use sunlight to make food (page 14)
National Geographic Explorer, Pathfinder
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Explore the Article
page 12
page 13
Read and Discuss the Science
page 14
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Have students look at the picture of the snake on page 12 and read the caption. Then read the introduction. Ask: How does the introduction show the role of the saguaro cactus in the desert? Prompt students to include the details of the birds, bats, and javelinas. If students are unfamiliar with a javelina, explain that it is a medium-sized, wild animal that looks like a pig. Read page 13 with students. Have students think about how each section subhead gives a clue to its main idea of that section. Discuss the adaptations that help the cactus survive in the desert. Ask students to find four physical adaptations of the saguaro cactus. Lead students in a discussion of how these adaptations benefit the plant. (Its thick, waxy skin traps water. Its spines protect it from animals eating it. Its roots spread out far and are not deep so that it can soak up water quickly when it rains. Its stem is a water storage tank.)
Build Comprehension
Point out to students that in the introduction on page 12, the writer gives important details. These lead up to that section’s main idea in the last sentence, “In the parched and scorching desert, the saguaro is the center of life.” Highlight this sentence in your digital edition. Then model how to summarize “Skin Deep.” Help students find the main idea and important details, such as: The desert is a harsh environment, so the saguaro has adaptations to help it survive. For example, its skin is thick and waxy with rows of spines.
Read and Discuss the Science
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Before reading pages 14-15, call attention to the three animals in the photos. Point out that in each, the cactus provides something different for the animal. Read “Good to Grow” with students. Explain that photosynthesis is a process all plants use to grow. Point out that photomeans “light” and synthesis means making something by combining different things. So photosynthesis means that plants use sunlight to turn water and carbon dioxide into food. Display the poster and have students explain the cactus’s photosynthesis. Have students read “Late Bloomer.” Ask: Why do bats and doves only feed on the cactus flowers at night? (The flowers close during the day.) Then have students read the sections “Home Sweet Home” and “Branching Out.” List the types of animals described in these sections and ask students to discuss how each animal uses the saguaro.
Build Comprehension
Remind students that they can use the summaries of sections of an article to summarize the entire article. Have students work in groups to summarize “Center of Life.” Be sure students mention the saguaro’s life cycle, its adaptations, and the ways it helps other animals survive.
Support Struggling Readers Before reading page 12, note the sentence at the end of the fourth paragraph in the introduction, “Food is hard to come by.” Explain that this expression means “difficult to find.”
National Geographic Explorer, Pathfinder
page 15
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Support Struggling Readers Before reading page 14, point out the subhead, “Late Bloomer.” Tell students that this phrase usually refers to a person or animal for whom it takes longer for something to happen than it does for others. For example, most baby birds learn to fly after a few weeks. If a baby bird takes more time to learn, it could be said that it is a “late bloomer.” In this article, the subhead is a play on words. Here, it means that the cactus’s flowers bloom late, or bloom at night.
October 2011
Extend Science Learning
Evaluate
Divide students into groups. Have each group choose one of these activities that either demonstrate how a cactus moves water inside the plant or the parts of a cactus: 1. Use a rectangular strip of paper towel to demonstrate how roots take up water. On one of the short sides, cut a series of slits, or “fingers,” ending about halfway up the towel. Place the fingers in a shallow dish with a small amount of water. Have students observe the water travelling up the paper towel. If you wish, add food coloring to the water for added effect. 2. Place a white flower such as a carnation in a clear plastic cup filled with water. Add 10-20 drops of food coloring to the water. Let the flower sit overnight. Then have students observe what happened to the color of the petals and make inferences about why they changed color.
National Geographic Explorer, Pathfinder
When students have finished reading, review the learning objectives listed on page T6. Share the objectives with students and have them do a self-evaluation of their learning.
Fast Facts • Saguaros begin to grow flowers when they are 35 years old. They begin to grow arms when they are 50-75 years old.
3. Provide two live cacti for students to observe. Carefully cut one cactus in half vertically so students can see a cross-section of the cactus’s interior. Leave the other cactus intact. Have students make a drawing showing the parts of the cactus they can see. When groups have finished their projects, have them prepare a presentation to share with the class.
Have students complete the blackline master while they read. Or have groups work together to complete it after reading. Use their responses to evaluate their understanding of the content and vocabulary. Have students share their responses, and address any misconceptions.
• Saguaros grow only in the Sonoran Desert, which is located in parts of the United States and Mexico. • Some people use parts of the saguaro for food. The make flour, cakes, and jam from the saguaro’s fruit, pulp, and seeds. • The state of Arizona has a Saguaro Harvest celebration every year.
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Center of Life
Name:
Before Reading 1. C hoose the correct Wordwise words to complete this paragraph.
Many animals survive in a desert __ __ __ __ __ __ __ __ __ by using the saguaro cactus as their __ __ __ __ __ __ __. That’s because the saguaro cactus has different __ __ __ __ __ __ __ __ __ __ __ for storing water. It uses a process called __ __ __ __ __ __ __ __ __ __ __ __ __ __ to make food.
During Reading Different animals rely on the saguaro cactus to survive. As you read, keep track of these animals. Tell what the cactus provides.
Animals
National Geographic Explorer, Pathfinder
What the Cactus Provides
Page T11
October 2011
Copyright Š 2011 National Geographic Learning. Teachers may copy this page to distribute to their students.
2. T ell what you already know about cacti. Does anyone you know have a cactus plant? Think about where cacti live, what they look like, and what role they play in an ecosystem.
Center of Life
Name:
After Reading In the Sonoran Desert, the saguaro cactus is the “center of life.” Use the cactus below to draw or tell what this means. Be sure to show the parts of the cactus that help it survive and the animals that need the cactus to live.
Copyright © 2011 National Geographic Learning. Teachers may copy this page to distribute to their students.
Example: Bats drink the nectar from the cactus’s flowers.
© TRIBALIUM/SHUTTERSTOCK
National Geographic Explorer, Pathfinder
Page T12
October 2011
Center of Life ANSWERS Before Reading 1. Choose the correct Wordwise words to complete this paragraph.
e __ c __ o __ s __ y __ s __ t e__ m Many animals survive in a desert __ __ by using the h __ a __ b __ i __ t __ a __. t That’s because the saguaro cactus saguaro cactus as their __ d __ a __ p __ t __ a __ t __ i o__ n s for storing water. It uses a process has different a __ __ __ __ p __ h __ o __t __ o __ s __ y __ n __t __ h __ e __ s __ i __ s to make food. called __
2. T ell what you already know about cacti. Does anyone you know have a cactus plant? Think about where cacti live, what they look like, and what role they play in an ecosystem.
During Reading Different animals rely on the saguaro cactus to survive. As you read, keep track of these animals. Tell what the cactus provides.
Animals
What the Cactus Provides
bats, doves, insects, birds, javelinas, squirrels, rats, mice, rabbits
food
gray bird, elf owl, Gila woodpecker, hawks, bobcat, scorpions
shelter/protection
water
jackrabbit
National Geographic Explorer, Pathfinder
Page T13
October 2011
Center of Life ANSWERS After Reading In the Sonoran desert, the saguaro cactus is the “center of life.” Use the cactus below to draw or tell what this means. Be sure to show the parts of the cactus that help it survive and the animals that need the cactus to live. Example: Bats drink the nectar from the cactus’s flowers.
The cactus has thick, waxy skin that keeps water in.
Birds and insects eat the cactus fruit’s pulp.
Birds build nests in the cactus’s arms and inside its stem.
The cactus grows sharp spines to keep animals from biting it.
Other animals eat the plants that grow in the cactus’s shade.
Javelinas, ground squirrels, and kangaroo rats eat the fruit.
The stem stores water. Mice and rabbits eat the black seeds from the fruit.
The cactus grows shallow roots to quickly suck up water when it rains.
© TRIBALIUM/SHUTTERSTOCK
National Geographic Explorer, Pathfinder
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October 2011
Engage Students Article Preview and Prior Knowledge
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Before students preview the article, have them read the headline “Extreme Life” and study the photo of the creature on page 16. Have students read page 17. Ask: What do animals need to survive? (food, air, shelter) Have students share what they know about places with extreme conditions that would harm most life on Earth. (the arctic, deserts, etc.) Lead a discussion about what it means to be “extreme.” page 16
page 17
Introduce Vocabulary
Overview
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Project Wordwise on page 23 of the digital edition on your interactive whiteboard or any white wall to preview the vocabulary words. Ask students if they know something about each word or if the word is new for them. The read aloud the words and definitions with the class.
Extreme Life Summary
Three scientists explore some of the most dangerous places on Earth. From a polar sea that is so cold it will kill an unprotected diver in two minutes to caves with toxic gases that are deadly to humans, these scientists are willing to risk their lives to learn more about how organisms survive in these extreme environments.
Copy the word web on page T18 and hand it out to students. Pair students and have them choose one of the words from Wordwise. Ask them to write the chosen word in the middle of the word web and then complete the web with as many meanings and examples as they can brainstorm. Invite students to share their webs with the rest of the class. Ask students who made webs for the same word to offer any additional meanings and examples.
Learning Objectives
As students read this article, they will: • know that in any particular environment, some organisms survive well, some survive less well, and some cannot survive;
Introduce the Comprehension Strategy
• understand that organisms have adaptations that allow them to survive; • understand that organisms fill a specific niche in their environment; • compare and contrast to aid comprehension.
basic need: something an organism can’t survive without, such as food (page 17) larva: the young form of some animals (page 21) niche: the role of an organism in an ecosystem (page 21) nutrient: a substance in food that a living thing needs to live and grow (page 22)
Compare and Contrast Explain that comparing and
contrasting information can help readers understand an article better. As students read, they should look for ways that two or more things are the same or different.
National Geographic Connection Learn more about National Geographic Explorer Kenny Broad at http://www. nationalgeographic.com/field/explorers/ kenny-broad
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Tell students that this article is about organisms that live in extreme environments. As they read, students should note the similarities and differences among these environments and the organisms that live there. If you wish, have students use the Compare/Contrast Matrix in the During Reading section of the blackline master to compare and contrast as they read.
Wordwise
National Geographic Explorer, Pathfinder
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October 2011
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Explore the Article
page 18
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Read and Discuss the Science
page 20
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Tell students that Antarctica is colder than anywhere else on Earth. It has the world’s lowest recorded temperature, -89° Celsius (-129° Fahrenheit). The average summer temperature is only -7° Celsius (20° Fahrenheit). Help students compare these temperatures to the average temperatures for your area. Then have students read page 18. Have students connect the dangers listed with what Kim does to protect herself. (no air, brings an air tank; no light; brings a flashlight; extreme cold, wears a diving suit)
Read and Discuss the Science
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Before reading pages 20-21, point out the photos of the cave. Ask students what they know about caves from personal experiences, books, or other resources. Read page 20 with students. Have student volunteers find and identify two adaptations described in this section. (Bats hang from the ceiling where the air is less toxic. The pink and silver fish have special blood that catches and holds a lot of oxygen.) Remind students that plants use sunlight to produce their own food. But here, there is no sunlight.
Have students look at the pictures on pages 18-19 and read the captions. Point out that “slowly” and “tiny” are clues to how organisms in this environment survive. Then read the sections “Cold and Slow” and “A Coming Feast.” If needed, explain that adaptations are how organisms change over time to better fit their environment. Discuss the adaptation of the ice fish. Note the sentence: “In fact, this fish needs the extreme cold.” Explain that the all organisms have adaptations to help them survive. Discuss the adaptations of the other organisms described on page 19.
Then have students read “Cave Slime.” Have students find the source of energy described in this section. (the poisonous gas) Ask: Why do the midge larvae feed on slime? (The slime is bacteria that provide nutrients for the midge larvae to grow.) How do the bacteria make food without sunlight? (They use toxic gas.) Explain: These bacteria play a key role in this food chain. The larvae eat the slime and grow into midges. Spiders eat the midges. Other animals eat the spiders. Ask: How are the bacteria like plants in other food chains? (They are the producers.)
Build Comprehension
After students have read pages 18-19, have them compare what Kim needs to survive with what the organisms mentioned need. Students should focus on temperature, air, light, and energy.
After students have read pages 20-21, have them compare the cave to the Ross Sea. Ask: What is similar about these environments? What is different? Then have students compare the organisms that live in each place and the adaptations they have developed in order to live there.
Support Struggling Readers
Support Struggling Readers
Before reading page 19, point out the subhead, “A Coming Feast.” Explain that the word feast means a special meal with a lot of food. The word coming in this phrase means “upcoming.” So the phrase means that a big meal will happen soon.
National Geographic Explorer, Pathfinder
Build Comprehension
Point out the word toxic in the first paragraph on page 20. Explain that toxic is another word for poisonous. Point out the Wordwise word larvae on page 21. Explain that larvae is the plural form of the word larva.
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eExtend Science Learning
Explore the Article
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Divide students into groups. Have each group imagine that they are scientists in the location of their choice: Antarctica, Cueva de Villa Luz, Mexico, or blue holes in the Bahamas. Have students prepare a report explaining the purpose of their trip and why it’s beneficial to know how some organisms survive in this extreme environment. They should also explain how it’s dangerous for them and why it’s worth the risk, if it is. page 22
page 23
Read and Discuss the Science
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Have students look at the photos of the diver squeezing through the narrow cave opening in on page 22 and the divers with their flashlights on page 23 and read the captions. Then read the introductory paragraphs. Lead a discussion of how these dangers are like and unlike those in the first two extreme environments. Review the tools the explorer uses for safety and how these are similar and different from the tools that the other two scientists use. Then read the section, “Entering the Maze,” with students. Discuss how the team needs to prepare and what they encounter as they enter the blue hole. Have students read the section, “Around the Corner.” Discuss why the organisms that survive well here must be small. (There’s little food or oxygen.) Have students compare the niche of some of the bacteria in these underwater caves with the bacteria in the cave in Mexico. (The bacteria eat toxic gases and then become food for other organisms.)
Alternatively, use the Explorer website (ngpathfinder.org) to have students send e-cards of other extreme environments and take the poll, “Which extreme environment would you like to visit?” Note that depending on internet connection speeds, the e-cards may take some time to load.
Evaluate When students have finished reading, review the learning objectives listed on page T11. Share them with students and have them do a self-evaluation of their learning.
Fast Facts • Antarctica is the coldest, windiest, driest, iciest, and highest land mass on Earth. It has longest nights and the longest days. • Blue holes got their name from the dark blue color of water caused by their depths.
Finally, ask students to respond to the last paragraph by telling whether they think learning about how these organisms live is worth the risks of exploring these extreme environments.
Build Comprehension
When students have finished reading pages 22-23, have them again compare the environment with the previous environments.
Support Struggling Readers Point out the first sentence in the third paragraph in “Entering the Maze.” Explain that the phrase “At 9 meters (30 feet)” means 9 meters (30 feet) below the surface of the blue hole. National Geographic Explorer, Pathfinder
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Extreme Life
Name:
During Reading
Copyright Š 2011 National Geographic Learning. Teachers may copy this page to distribute to their students.
Write a word from Wordwise in the middle circle. Then complete the web with as many meanings and examples as you can think of.
National Geographic Extreme Explorer
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Extreme Life
Name:
Before Reading 1. E ach of the Wordwise words in the first column below have a synonym somewhere in the Word Soup in the third column. Find the best synonym, and write it in the middle column, In Other Words. Use a dictionary if you need help.
In a Word Wordwise
In Other Words
Word Soup
basic need
habitat young organism
larva
plant necessity consume place
niche
adapt worm food useful bacteria tools environment
nutrient
2. W hat might make an environment hard for some organisms to survive well? Read the list of environments below. Tell what you think might be a problem for living things there.
Environment
Survival Problems
in the ocean under ice
Copyright Š 2011 National Geographic Learning. Teachers may copy this page to distribute to their students.
inside a volcano on a dry and hot desert deep underground in a dark cave filled with toxic gas
National Geographic Explorer, Pathfinder
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October 2011
Extreme Life
Name:
During Reading 1. A s you read, use the chart below to show the similarities and differences among the environments, their organisms, and the organisms’ adaptations.
Compare/Contrast Matrix Location
Type of Environment
Type of Organisms in this Environment
Adaptations to Survive
The Ross Sea, Antarctica
Blue hole, The Bahamas
After Reading Imagine an extreme environment. Describe what it is like. Then imagine some organisms that might live there. Tell what adaptations they would need to have to survive.
National Geographic Explorer, Pathfinder
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October 2011
Copyright Š 2011 National Geographic Learning. Teachers may copy this page to distribute to their students.
Cueva de Villa Luz, Mexico
Extreme Life ANSWERS Before Reading 1. E ach of the Wordwise words in the first column below have a synonym somewhere in the Word Soup in the third column. Find the best synonym, and write it in the middle column, In Other Words. Use a dictionary if you need help.
In a Word Wordwise
In Other Words
Word Soup
basic need
necessity
habitat young organism
larva
young
plant necessity consume place
niche
place
adapt worm food useful
nutrient
food
bacteria tools environment
2. W hat might make an environment hard for some organisms to survive well? Read the list of environments below. Tell what you think might be a problem for living things there.
Environment
Survival Problems
in the ocean under ice
extreme cold
inside a volcano
extreme heat
on a dry and hot desert deep underground in a dark cave filled with toxic gas
National Geographic Explorer, Pathfinder
heat, little water poisonous gas, darkness
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Extreme Life ANSWERS During Reading 1. A s you read, use the chart below to show the similarities and differences among the environments, their organisms, and the organisms’ adaptations.
Compare/Contrast Matrix Location
The Ross Sea, Antarctica
Type of Environment
Type of Organisms in this Environment
Adaptations to Survive
very cold; dark; wet; ice; sea; little food or light
plankton; pale ice fish; a giant jelly fish; red sea stars; a big volcano sponge; giant white sea star; plant algae
fish with special blood that doesn’t freeze; slow growing and slow-moving animals that use little energy; algae that grow thick during the summer and feed other animals
bats; eels; pink and silver fish; spiders; tiny flies called midges; larva; bacteria
bats that stay up high to avoid poison gases; fish with special blood that holds a lot of oxygen; midge larvae that eat slime bacteria; bacteria that doesn’t need sunlight; bacteria that needs toxic gas
Cueva de Villa Luz, Mexico
dark; air filled with toxic gases; streams; cave
Blue hole, The Bahamas
dark; toxic gases; underground, saltwater caves like a maze; little food or oxygen
bacteria; tiny shrimps; remipedes
bacteria that eat salt and chemicals; bacteria eat toxic gases; small organisms that need less energy to grow
After Reading Imagine an extreme environment. Describe what it is like. Then imagine some organisms that might live there. Tell what adaptations they would need to have to survive.
National Geographic Explorer, Pathfinder
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October 2011