Lesson 5 r

Cause and Effect

Infroducfion

NGSSS LA.7.1.7.4: Identify cause-and-effect relationships in a text

Imagine you are eagerly awaiting a concert by your favorite band. At the last minute, you find out the concert has been canceled. Why? A snowstorm has shut down the airports all across the region, and the band members cannot fly in.

Why did something happen? That's a question we ask ourselves often. We want to know the reason, or cause, of an event or action. Likewise, we often want to know what will happen as a result, or effect, of an event or action, in the example above, the canceled concert is the effect (what happened), and the snowstorm is the cause (why it happened).

When you read, you will also come across cause-and-effect relationships. For example, an article titled "Start Exercising Today" will likely describe the positive effects of getting exercise. Writers often use cause and effect in texts that explain something or try to persuade the reader. But any kind of text, including stories, can use cause and effect.

How do you spot examples of cause and effect? One way is to look for signal words such as because, since, so, therefore, consequently, due to. and as a result. Writers use these words when they clearly state a cause-and-effect relationship. But sometimes the relationship is implied rather than stated, in that case, you must "read between the lines" to infer causes and effects.

When thinking about cause and effect, remember that a cause may have more than one effect, and an effect may have more than one cause. Also, cause-and-effect events may occur in a chain. In a cause-and-effect chain, a cause leads to an effect, and that effect becomes the cause of another effect, and so on.

Becoming aware of causes and effects will help you understand what you read. The following chart shows a few examples of cause and effect.

Cause missed the bus

Effect late for school

studied for test received a good grade on test r ^ ^ H understand cause-and-effect read this lesson relationships in a text

Read this article about an Arctic animal. Think about the events that are described and why they happen.

Little Lemmings 1 The brown lemming is a fur ry rodent that looks like a chubby hamster. Although

it is small, i t plays a big role i n the food chain of the Arctic tundra, where it lives. Lemming populations rise and fall i n a roughly four-year cycle. When the grasses, mosses, and roots that lemmings eat are abundant, the lemmings reproduce quickly. Each female may have up to eight young every five weeks. As the population grows, the lemmings use up the available food sources, and their l i v i n g area becomes crowded. As a result, thousands of lemmings migrate to a new area.

2 As they migrate, many lemmings starve or d r o w n as they t ry to s w i m across rivers and lakes. This, plus being eaten by predators while on the r u n , leads to a dramatic drop i n their population.

What effects occur when lemmings have an abundant supply of food?

What events concerning lemmings does the article explain? W h y lemming populations rise and fall .

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How does an abundant food supply affect lemming reproduction? Female lemmings have more babies.

As the lemming population grows, what happens? The lemmings eat up all the available food i n the area and then migrate i n large numbers to f i n d more food.

ANSWER! When lemmings have an abundant food supply, their population grows rapidly. They eat up al l the available food i n an area and must migrate to f ind more.

read the article to answer this question.

What are the causes of the dramatic drop i n lemming populations?

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NGSSS LA.7.1.7.7 Florida

Read the passage. Use the Think About It to guide your reading. Then answer the question. Use the Hint to help you.

Think About It What announcement is made? Why doesn't Gina respond to it?

Hint Notice the word because. What is the cause of Gina's situation?

Oh, No! . 1 Gina strolled down the aisle, scanning the call numbers. When

she spotted the book she was looking for. Mummies of Ancient Egypt, she pulled i t from the shelf. Opening the large book to a page i n the middle, she saw a fascinating picture of a cat mummy. She immediately sat down on the floor and started reading.

2 Each page she turned to had another in t r iguing picture that made her want to read more. She sat quietly absorbed i n her book for over 30 minutes. Even the voice making an announcement on the loudspeaker d id not disturb her. When she finally looked up, she noticed that there was no one around. I n fact, almost all of the lights i n the l ibrary had been turned off. "Oh, no!" she thought. "The l ibrary is closed!" She quickly called her m o m on the phone.

Gina found herself in the library after it closed because A she had been talking to a librarian for over 30 minutes. B she was completely caught up i n the book she was reading. C she could not figure out how to use the phone to call her m o m . D she wanted to try reading all through the night at the l ibrary.

CORRECT ANSWER

SUPPORTING DETAILS

INCORRECT ANSWERS

Answer choice B is correct.

The text includes details that show Gina was caught up i n her book. She was absorbed i n her book for over 30 minutes. Because of this, she didn't take notice of the announcement about the l ibrary closing.

A is not correct because the passage does not mention a l ibrarian. C is not correct because Gina was able to use the phone to call her mom. D is not correct because the story details suggest that what happened was

unplanned.

Florida NGSSS LA.7.1.7.7

Read the passage. Use each Think About It to guide your reading.

Think About It Fire Safety Tips

What are some of the "dos and don'ts" of planning an escape route? What are the reasons for these dos and don'ts? Are the reasons stated or implied?

What should you do if someone gets burned? Why?

What reason is given for crawling on your hands and knees if you must exit through smoke?

1 Install and maintain smoke detectors—Smoke detectors warn you of fire i n time to let you escape. Install them on each level of your home and outside each sleeping area. Test them once a week, and replace batteries twice a year, or when the device chirps to signal a dead battery!

2 Plan and practice your escape—If fire breaks out i n your home, you must get out fast. W i t h your family, plan two ways out of every room. Fire escape routes must not include elevators because they might take you right to the fire. Choose a meeting place outside and stay there! Have the whole family practice the escape plan twice a year.

3 Space heaters need space—Keep portable space heaters at least 3 feet (1 meter) f rom paper, curtains, furni ture , clothing, bedding, or anything else that can burn . Never leave heaters on when you leave home or go to bed, and keep children and pets well away from them.

4 Be careful cooking—Keep cooking areas clear of combustibles, and don't leave cooking unattended. Keep pot handles turned inward so children won't knock or p u l l them over the edge of the stove. I f grease catches fire, carefully slide a l i d over the pan to smother the flames, and then t u r n off the burner.

5 A match is a tool for a d u l t s — I n the hands of a ch i ld , matches or lighters are extremely dangerous. Store them up high where kids can't reach them. A n d teach your children from the start that matches and lighters are tools for adults, not toys for kids. I f children f ind matches, they should tell an adult immediately.

6 Cool a b u r n — I f someone gets burned, immediately place the wound i n cool water for 10 to 15 minutes to ease the pain. Do not use butter on a b u r n , since this can keep the skin from cooling and further damage i t . I f a b u r n blisters or chars, see a doctor immediately.

7 Stop, drop, and roll—Everyone should know this rule: I f your clothes catch fire, don't r u n ! Stop where you are, drop to the ground, and ro l l over and over to smother the flames. Cover your face w i t h your hands to protect your face and lungs.

8 Crawl low under smoke — I f you encounter smoke using your pr imary exit, use your alternate route instead. I f you must exit through smoke, clean air w i l l be several inches off the floor. Therefore, you should get d o w n on your hands and knees, and crawl to the nearest safe exit.

NGSSS LA.7.1.7.7 Florida

Hints

Reread the second tip. What word signaling cause and effect can you find in this paragraph?

Reread the tip "Cool a burn." Look for a phrase that states the reason for placing the wound in cool water.

Reread the last tip. Do you see a word that clearly signals a cause-and-effect relationship? Identify the effect (what you should do) and the cause (why you should do it).

Use the Hints to answer the questions below. Circle the correct answers and provide supporting details from the passages.

1 According to the Ust of tips, why should an escape route f rom a fire not include elevators? - ' - . i : . A They could take you right to the fire. B They often stop working dur ing a fire. C They operate slowly dur ing a fire. D They can only carry one family at a time.

Supporting Details:

I f someone is burned, the reason for placing the wound i n cool water for 10 to 15 minutes is to A hold i n the heat. B ease the pain. C heal a b u r n blister. D save a t r ip to the doctor.

Supporting Details: '

According to the list of tips, i f you crawl low under smoke to exit a burning bui lding, then you w i l l be able to A see your way out. B breathe clean air near the floor. C avoid getting burned on your head. D exit the bui ld ing faster. "

Supporting Details:

SHARE With your partner, share and discuss your answers and supporting details.

Florida NGSSS LA.7.1.7.7

Read the article "Spiders: In Pursuit of Prey" before answering Numbers 1 through 6.

Spiders: In Pursuit of Prei^ By Harry Gardner

Have you seen a spider today? I f you have, that's not surprising. Spiders live everywhere, indoors and out. They have adapted to l i v i n g i n deserts, caves, h igh mounta in peaks, and even under water. There are more than 36,000 k n o w n species. I n natural environments, scientists estimate that the number of spiders per acre can be tens of thousands up to several m i l l i o n . I n fact, according to spider experts, you are probably 6 feet f r o m a spider r ight now!

Spiders are the most common predator on earth. They eat main ly insects. Because spiders are so numerous and widespread, they are very important i n controlling insect populations, including pest insects.

Many people t h i n k that spiders themselves are insects. I n fact, they belong to a class of animals called arachnids. Scientists classify spiders this way because they have t w o main body parts (insects have three) and because they have eight legs (insects have six). Spiders share these features w i t h other arachnids, such as scorpions, ticks, mites, and daddy longlegs. Both arachnids and insects belong to a larger group of animals called arthropods, w h i c h have a hard exoskeleton that covers the body.

As predators, spiders are fascinating animals. M a n y of them use an ingenious tool to catch their prey: a web made of silk. A l l spiders have the abil i ty to produce silk f r o m glands i n their abdomen. Using its t w o h i n d legs, a spider can "reel o u t " a fine strand of si lk as i t constructs its web.

Some spiders that b u i l d webs, such the common yellow-and-black garden spider, can produce

different k inds of silk. They use a strong, stretchy silk to b u i l d the basic framework and add a sticky variety that makes i t hard for a trapped insect to get away. Spider silk, w h i c h is made up of protein, is extremely flexible but stronger than steel!

The garden spider weaves an elegant snare called an orb web. This type of web is basically round, w i t h spokes l ike a bicycle wheel and many strands connecting the spokes. Some orb weavers lie i n wai t for their prey at the center of the web. Others attach a trap line to the center of the web

and then hide nearby, h o ld in g onto the line. When a s truggl ing insect causes the line to vibrate, the spider springs into action. The o i l coating on its feet helps it glide across the sticky threads of the web. W h e n it reaches its prey, the spider usually bites it , injecting paralyzing venom, and then wraps it i n silk.

I f the spider is l iungry, i t starts digesting the prey r ight away. Since spiders don't have teeth, they must break d o w n their food i n another way. They actually do this outside their bodies, by spitting digestive juices onto the insect that begin to l iquefy it. Then it can suck d o w n part of its meal a little at a time.

Other spiders weave different types of webs. Some b u i l d triangle webs, w h i c h look l ike a section of an orb web, and wai t for their prey at one end corner of the web. Others b u i l d small sheet webs between tal l blades of grass or branches of shrubs. Directly above this sheet, the spider may spin a net of nonsticky threads. The net causes a flying insect to lose its balance and fal l onto the sheet, where the spider is l u r k i n g . Finally, many indoor spiders b u i l d tangle webs, or cobwebs, often i n the corner of a room. They may look messy, but they are effective i n catching prey.

As a spider web gets used to catch meals, it becomes damaged and requires repairs. Orb weavers often b u i l d a new web every day, a task that can take less than 30 minutes. If the web damage is minor , the spider repairs it , often eating parts of the old web to conserve silk.

About half of a l l spiders, inc luding the j u m p i n g spider and the w o l f spider, do not b u i l d webs to catch their food. Sometimes called wander ing spiders, they f i n d h i d i n g places and wai t for passing prey. Unl ike web-builders, these hunters have excellent eyesight. W h e n a wanderer sees an insect nearby, or feels its movement, i t rushes out, pounces on its pray, and paralyzes it w i t h a bite. Then it settles d o w n for a nice lunch.

A l t h o u g h large spiders such as the black w i d o w are often featured i n scary movies, most spiders are small and harmless to humans. They are useful animals and amazing food-catchers w i t h unusual habits that are fascinating to observe.

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Florida NGSSS LA.7.1.7.7

Spiders are very effective i n controlling insect populations because

A. they can produce silk.

B. they are fascinating animals.

C. they are numerous and widespread.

D. there are more than 36,000 known species.

Because spiders have two main body parts and eight legs, they are classified as

F. insects. . ^

G. animals.

H. arachnids.

I. arthropods.

According to the article, what allows wandering spiders to catch prey?

A. excellent eyesight

B. sensing vibrations

C. the webs they bui ld

D. a strong sense of smell

What effect does the net of nonsticky threads above a sheet web have?

F. The net traps and holds a f lying insect.

G. The net gives the spider a place to wait .

H. The net keeps other spiders out of the sheet web.

I. The net causes a flying insect to fall onto the sheet web.

H o w is a spider able to break d o w n food outside of its body?

A. B. C. D.

by wrapping its prey in silk

by paralyzing its prey w i t h venom

by spitting digestive juices onto the prey

by chewing small bites and spitting them out

You have probably seen a spider today because

F. spiders live mainly indoors.

G. spiders are common i n schools.

H. spiders are large and easily seen.

I. spiders live i n many kinds of environments.

Answer Form

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