Key Concepts in Science
GRAVITY
TEACHER GUIDE
© 2015 Sally Ride Science
GRAVITY: CONTENTS
Student handouts are at the back of the Teacher Guide.
Correlation to Standards ............................................................................................................................. 3-4
Sally Ride Science Teacher Guides ................................................................................................................ 5
Gravity: About the Book .................................................................................................................................. 6
Getting Started: In Your World .........................................................................................................................7
Preview Gravity, read the introduction, and discuss key concepts.
Chapter 1: Gravity Basics ................................................................................................................................ 8
Model taking notes as you read, read Chapter 1, and discuss key concepts in the chapter.
Students: Chapter 1 handout
Chapter 2: Gravity on Earth ............................................................................................................................ 9
Model asking questions as you read, read Chapter 2, and apply key concepts in the chapter.
Students: Chapter 2 handout
Science Writing ...............................................................................................................................................10
Write about how gravity affects a sport.
Students: Science Writing handout
Read Chapter 3: Gravity in the Universe ................................................................................................. 11-12
Model summarizing with a concept map, read Chapter 3, and create a class concept map.
Students: Chapter 3 handout
Thinking Like a Scientist................................................................................................................................. 13
Calculate weight on different bodies in the solar system.
Students: Thinking Like a Scientist handout
How Do We Know?
> Read How Do We Know? ........................................................................................................................ 14
Read about astronomer Dara Norman and answer the questions.
Students: How Do We Know? handout
> Math Connection ..................................................................................................................................... 15
What would your weight be on other bodies in space?
Students: Math Connection handout
> Write a Science Article ............................................................................................................................ 16
Research and write about the Hubble Space Telescope.
Students: Write a Science Article handout
Study Guide: Hey, I Know That! ...................................................................................................................... 17
Complete the study guide questions.
Students: Hey, I Know That! handout
© 2015 Sally Ride Science
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CORRELATION TO STANDARDS
Correlation to Science Standards
For information on alignment to state science standards and NGSS, visit
https://sallyridescience.com/learning-products/product-standards
Correlation to Common Core
Sally Ride Science’s Key Concepts and Cool Careers book series provide students with authentic literacy experiences
aligned to Common Core in the areas of Reading (informational text), Writing, Speaking and Listening, and Language
as outlined in Common Core State Standards for English Language Arts & Literacy in History/Social Studies,
Science, and Technical Subjects. Gravity: A Universal Tug-of-War and the accompanying activities align to the
following standards:
Reading Standards for Literacy in Science and Technical Subjects 6-12 (RST), Grades 6-8
Key Ideas and Details
1. Cite specific textual evidence to support analysis of science and technical texts.
2. Determine the central ideas or conclusions of a text; provide an accurate summary of the text distinct from prior
knowledge or opinions.
Craft and Structure
4. Determine the meaning of symbols, key terms, and other domain-specific words and phrases as they are used in
a specific scientific or technical context relevant to grades 6-8 texts and topics.
Integration of Knowledge and Ideas
7. Integrate quantitative or technical information expressed in words in a text with a version of that information
expressed visually (e.g., in a flowchart, diagram, model, graph, or table).
Range of Reading and Level of Text Complexity
10.By the end of grade 8, read and comprehend science/technical texts in the grades 6-8 text complexity band
independently and proficiently.
Writing Standards for Literacy in History/Social Studies, Science, and Technical Subjects 6-12 (WHST),
Grades 6-8
Text Types and Purposes
1. Write arguments focused on discipline-specific content. a.-e.
2. Write informative/explanatory texts, including the narration of historical events, scientific procedures/
experiments, or technical processes. b., d., f.
Production and Distribution of Writing
4. Produce clear and coherent writing in which the development, organization, and style are appropriate to task,
purpose, and audience.
6. Use technology, including the Internet, to produce and publish writing and present the relationships between
information and ideas clearly and efficiently.
Research to Build and Present Knowledge
7. Conduct short research projects to answer a question (including a self-generated question), drawing on several
sources and generating additional related, focused questions that allow for multiple avenues of exploration.
8. Gather relevant information from multiple print and digital sources, using search terms effectively; assess the
credibility and accuracy of each source; and quote or paraphrase the data and conclusions of others while
avoiding plagiarism and following a standard format for citation.
© 2015 Sally Ride Science
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CORRELATION TO STANDARDS
9. Draw evidence from informational texts to support analysis, reflection, and research.
Range of Writing
10.Write routinely over extended time frames (time for reflection and revision) and shorter time frames (a single
sitting or a day or two) for a range of discipline-specific tasks, purposes, and audiences.
Speaking and Listening Standards 6-12 (SL), Grades 6-8
Comprehension and Collaboration
1. Engage effectively in a range of collaborative discussions (one-on-one, in groups, and teacher-led) with diverse
partners on grade 6, grade 7, and grade 8 topics, texts, and issues, building on others’ ideas and expressing their
own clearly. a.-d.
Presentation of Knowledge and Ideas
4. Present claims and findings, sequencing ideas logically and using pertinent descriptions, facts, and details to
accentuate main ideas or themes; use appropriate eye contact, adequate volume, and clear pronunciation.
Grade 6
Present claims and findings, emphasizing salient points in a focused, coherent manner with pertinent
descriptions, facts, details, and examples; use appropriate eye contact, adequate volume, and clear
pronunciation. Grade 7
Present claims and findings, emphasizing salient points in a focused, coherent manner with relevant evidence,
sound valid reasoning, and well-chosen details; use appropriate eye contact, adequate volume, and clear
pronunciation. Grade 8
Language Standards 6-12 (L), Grades 6-8
Vocabulary Acquisition and Use
4. Determine or clarify the meaning of unknown and multiple-meaning words and phrases based on grade 6, grade
7, and grade 8 reading and content, choosing flexibly from a range of strategies. a.-d.
6. Acquire and use accurately grade-appropriate general academic and domain-specific words and phrases; gather
vocabulary knowledge when considering a word or phrase important to comprehension or expression.
© 2015 Sally Ride Science
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SALLY RIDE SCIENCE TEACHER GUIDES
The Sally Ride Science Key Concepts in Science and Cool Careers book series are available as print books
and eBooks.* A Teacher Guide accompanies each of the 36 Key Concepts books and 12 Cool Careers books.
More information: sallyridescience.com/learning-products
*Book pages pictured in the Teacher Guides are from eBook editions. Some pages in the print books have different images or layouts.
Cool Careers
Cool Careers in Biotechnology
Cool Careers in Earth Sciences
Cool Careers in Engineering (Upper Elementary)
Cool Careers in Engineering (Middle School)
Cool Careers in Environmental Sciences (Upper Elementary)
Cool Careers in Environmental Sciences (Middle School)
Key Concepts in Science
Adaptations
Biodiversity
The Biosphere
Cells
Earth’s Air
Earth’s Climate
Earth’s Energy
Earth’s Natural Resources
Earth’s Water
Elements and Compounds
Energy Basics
Energy Transformations
Cool Careers in Green Chemistry
Cool Careers in Information Sciences
Cool Careers in Math
Cool Careers in Medical Sciences
Cool Careers in Physics
Cool Careers in Space Sciences
Flowering Plants
Food Webs
Forces
Genetics
Geologic Time
Gravity
Heat
Life Cycles
Light
Motion
Organic Molecules
Photosynthesis and Respiration
Physical Properties of Matter
Plant and Animal Systems
Plate Tectonics
The Rock Cycle
Solids, Liquids, and Gases
Sound
Space Exploration
Sun, Earth, and Moon
Units of Measurement
Vertebrates
The Water Cycle
Weathering and Erosion
Sally Ride Science provides professional development and classroom tools to build students’
passion for STEM fields and careers. Founded by Dr. Sally Ride, America’s first woman in space,
the company brings science to life for upper-elementary and middle school students.
Visit us at SALLYRIDESCIENCE.COM for more information.
© 2015 Sally Ride Science
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GRAVITY: A Universal Tug-of-War
About the Book
Gravity: A Universal Tug-of-War uses real-world experiences to guide students to an understanding of the nature
of gravity. Students learn that gravity is a universal force acting between all objects. They discover how gravity holds
everything—including us—in place on Earth. They also learn how gravity determines the structure of our solar
system and the rest of the Universe—from galaxies like our own Milky Way to clusters of galaxies dotting the vast
expanse of space. At the end of each two-page spread, a brief statement called The Bottom Line reinforces students’
understanding by summing up the key ideas about gravity covered in those pages.
In Your World engages students’ interest with a vivid description of a real-world scene—a snowboarder racing
down a mountain. The brief scenario sets the stage for the chapters to follow by getting students to think about the
crucial role of gravity in this scene and in everything that happens in their world.
Chapter 1 explains that any two objects attract each other as a result of the force of gravity between them. Students
learn that the strength of the force depends on the masses of the objects and the distance between them. The
chapter also explains that gravity is a weak force compared to a force like magnetism.
Chapter 2 helps students see that gravity alone holds us to our planet’s surface, pulling everything toward the center
of Earth. The chapter presents the concepts of velocity and acceleration of objects falling to Earth, the influence of air
resistance on falling objects, and the difference between mass and weight.
Chapter 3 explores the role of gravity in the Universe by examining the formation of stars and planets, the effects of
gravity on solar systems and galaxies, and the gravitational pull of black holes.
Thinking Like a Scientist tells how some scientists apply their understanding of gravity in their work planning and
executing a mission to land a spacecraft on Mars. Students get a chance to interpret real science data.
How Do We Know? focuses on Dara Norman, an astronomer who uses the bending of light by gravity as a tool to
study distant galaxies. Then, in Math Connection, students apply what they’ve learned about gravity to calculate their
weight on different bodies in outer space.
Hey, I Know That! allows students to assess their own learning through a variety of assessment tasks relating to the
key concepts covered in Gravity.
© 2015 Sally Ride Science
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GRAVITY: GETTING STARTED
In Your World
Preview the book
Ask students to browse through Gravity. Encourage them to look at the cover, table of
contents, chapter titles, special features, photographs, and diagrams. Explain that paying
attention to these features will help them to understand the concepts in the book.
Read In Your World (pages 4 and 5) and discuss key concepts
Tell students to read In Your World. Then refer to some of the scenarios described in In Your
World. Ask students to think about what would happen in each case if gravity suddenly
stopped:
If gravity suddenly stopped, what would happen to a snowboarder? [If gravity suddenly
stopped, snowboarders who stepped onto their snowboards on the slope of a mountain
wouldn’t slide downhill—there would be no downward force tugging on them. In fact,
things that weren’t fastened down, including those snowboarders, would drift off of Earth’s
surface and into space.]
What would happen to falling rain? [If gravity stopped, water molecules that condensed
into raindrops wouldn’t fall from clouds—there would be no force pulling them toward the
ground. Earth’s atmosphere, including all the clouds and water vapor in it, would dissipate into space.]
What would happen to the planets orbiting the Sun? [Without gravity, the eight planets orbiting our Sun would
suddenly stop circling and travel in straight lines from whatever point they were at in their orbits.]
Ask several students to share their explanations with the class. Encourage other students to elaborate on the
explanations.
© 2015 Sally Ride Science
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GRAVITY: CHAPTER 1
Gravity Basics
Read Chapter 1: Gravity Basics
Before reading: Model taking notes as you read
Before students read Chapter 1 of Gravity, model how to take notes as you read. Call on a
student to read aloud the first paragraph on page 6. Then reread the text and think aloud
about how you would figure out the gist of the paragraph:
According to this paragraph, What goes up must come down describes how gravity works
on Earth. I’ll write that down in my notes.
Call on a student to read aloud the second paragraph and then point out the gist of the
information. Say,
In my notes, I’ll write, Gravity is a force. I’ll also write, Gravity pulls together any two
objects. And finally, I’ll note, Earth’s gravity pulls things down toward it.
Explain to students that taking notes will help them concentrate as they read. The notes
should be organized in a logical way so they become a tool for learning
and remembering. Explain that notes can consist of outlines, concept
maps, sketches, and combinations of words and diagrams—whatever
ADDRESS MISCONCEPTIONS
makes the notes meaningful.
Read Chapter 1: Gravity Basics (pages 6-9)
Ask students to read Chapter 1: Gravity Basics. Give them the Chapter
1 handout and tell them that using it as they read will sharpen their
note-taking skills. Point out that the handout has a place to make an
illustrated summary of key ideas in the chapter.
After reading: Discuss key concepts
Have pairs of students share their notes, discuss the main ideas of
Chapter 1, and refine their notes if they wish. Then ask,
Students may say they experience gravity
as a very strong force and think that
magnets are weak, since students can pull
objects away from a magnet. But since a
magnet can hold an object like a nail above
the ground, students should realize that the
force of the magnet on nail is stronger than
the force of gravity on the nail. Otherwise,
the nail would fall to the ground.
What is gravity? [Gravity is a force that pulls together any two objects.]
What does the strength of gravity between any two objects depend on? [The strength of gravity depends on two
things—the objects’ masses and the distance between them.]
If gravity acts on everything in the Universe, why isn’t everything clumped together into one big blob? [Objects in the
Universe aren’t all clumped together because each object attracts every other object with a force that depends on
their masses and the distance between them. So the farther apart the objects are or the less massive the objects,
the less the gravitational force. Earth is huge, so its gravitational tug on much less massive things like people, rivers,
trees, and the Moon is strong. In contrast, a grain of sand has very little mass, so its gravitational tug on people,
rivers, trees, and the Moon is very weak.]
© 2015 Sally Ride Science
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GRAVITY: CHAPTER 2
Gravity on Earth
Read Chapter 2: Gravity on Earth
Before reading: Model asking questions as you read
Begin by asking students to turn to page 11 in Gravity. Have them look at the diagram of a
falling basketball. Say,
The label on this diagram says Falling Objects Accelerate. The basketball in this diagram
is falling, and it is accelerating—it is moving faster and faster. But what is making the
basketball accelerate? I’ll write that question on the board.
Write down, What makes a falling basketball accelerate? Then call on a student to read the
text on page 11. Say,
Oh, now I understand. Gravity is making the ball accelerate as it falls. Everything accelerates
as it falls. But does everything accelerate at the same rate? That’s another question. I’ll look
for the answer as I read.
Tell students that coming up with questions—and looking for the answers—is an effective
way to improve their understanding of what they read.
Read Chapter 2: Gravity On Earth (pages 10-15)
Ask students to read Chapter 2. Give them the Chapter 2 handout and tell them to use it to
write down any questions that occur to them and any answers that they find as they read.
Note that the handout also has a space for students to make a diagram showing how a
falling object accelerates.
After reading: Apply key concepts
Direct students’ attention back to page 11 and the diagram of a falling basketball. Say,
Suppose you drop a penny from a height of 100 meters (328 feet). If the penny accelerates
at 9.8 meters per second squared, how far does the penny fall in the first second? In the
second second? In the third second? [During the first second, the penny falls 9.8 meters.
During the second second, it falls 19.6 m. During the third second, it falls 29.4 m. During the
fourth second, it falls 39.2 m.]
Tell students to work in pairs to draw a sketch of the penny being dropped from a height
of 100 meters, showing how far the penny falls each second until it hits the ground. Then
ask,
About how long would it take the penny to hit the ground? [It would take the penny about
4 seconds to hit the ground after being dropped from a height of 100 meters, or 328 feet
(9.8 m + 19.6 m + 29.4 m + 39.2 m = 98 m).]
Call on students to share their answers and explain how they arrived at those answers. As
a class, work to correct any misconceptions.
© 2015 Sally Ride Science
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GRAVITY
Science Writing
How gravity affects a sport
Give students the Science Writing handout. The handout asks students to choose a sport
and then answer questions about how gravity and air resistance affect that sport. Students
should write a paragraph for each question.
SAMPLE ANSWER
1. How does gravity affect the motion of players or equipment, such as a ball, when
the sport is being played? How would this change if Earth’s gravity were weaker or
stronger? [Sample paragraph for tennis: In the sport of tennis, gravity affects the
motion of the tennis ball on every shot. For example, when a tennis player smacks
a forehand over the net to her opponent, gravity pulls down on the ball, making it
fall in an arc back onto the court. Specifically, the force generated by the tennis
player’s muscles sends the ball flying forward at some speed while the force of
gravity tugs downward on the tennis ball at a speed of 9.8 m/s each second. The
ball’s downward speed would be faster if Earth’s gravitational pull were stronger,
and the ball would travel a shorter distance before hitting the court. The downward
speed would be slower if Earth’s gravitational pull were weaker, and the ball would
travel a longer distance before hitting the tennis court.]
2. How does air resistance affect the motion of the players or equipment? Do you
think this is a significant effect? Why or why not? [Sample paragraph for tennis:
Air resistance pushes up on a falling tennis ball, slowing its motion. Air resistance also pushes in the backward
direction as the ball moves forward. I think the backward effect can be significant, because the ball is moving
forward and downward, going through more air and hitting more air molecules.]
3. Suppose a player learns about the effects of gravity and air resistance. Describe a way that the player’s
performance could be improved by applying this knowledge to the game. [Sample paragraph for tennis: Knowing
that gravity causes the downward speed of the ball to increase 9.8 m/s each second, a tennis player might want
to hit more high lobs, since the downward speed of the ball increases rapidly, and it might be harder for the
opponent to return a high lob. The player could also take into account air resistance by determining the strength
and direction of the wind when deciding how hard and in which direction to hit the ball.]
© 2015 Sally Ride Science
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GRAVITY: CHAPTER 3
Gravity in the Universe
Read Chapter 3: Gravity in the Universe
Before reading: Model summarizing with a concept map
Before students read Chapter 3: Gravity in the Universe, give them the Chapter 3 handout.
Point out that it has a place for them to make a concept map summarizing the most
important points in the chapter.
To get students started, ask them to turn to page 16. Draw a circle on the board. Say,
This chapter is called Gravity in the Universe. That’s the main idea of the chapter, so I am
going to write that in the central circle of my concept map.
Then draw a second level of three or four circles with lines connecting them to the main
circle. Have a student read aloud the first two paragraphs on page 16. Ask,
What is an important idea about gravity in the Universe that we can write in our second
level of circles?
Listen to students’ responses and come to agreement on an
idea, such as, Our galaxy is held together by gravity. Write that
idea in one of the second-level circles. Then draw two or three
more circles connected by lines to that circle. Tell students that
the third-level circles are for adding more detail about the ideas
in the second level.
Tell students to copy the concept map onto their handouts.
As they read, they should complete the concept map of the
important ideas in Chapter 3.
Read Chapter 3: Gravity in the Universe (pages 16-23)
Ask students to read Chapter 3: Gravity in the Universe. Have
them take notes on the handout as they read and also complete
the concept map of the chapter.
After reading: Create a class concept map
After students finish reading Chapter 3, say,
SCIENCE BACKGROUND
Sir Isaac Newton realized that a force—gravity—
pulls an apple from a tree down toward the Earth.
And he realized that the same force that pulls
objects on Earth toward Earth’s center also could
pull objects in space toward Earth. The Moon stays
in orbit around the Earth because it is pulled by
Earth’s gravity, just as a falling apple is. But the
Moon never falls into the Earth. To explain this
phenomenon, Newton imagined a cannon on a tall
mountain. If the cannon shot a cannonball, gravity
would cause the cannonball to arc toward the
Earth. But if the cannonball had enough velocity, it
would never hit the Earth. The path of its arc would
match Earth’s curve, and the cannonball would
fall around and around the Earth. It would be in
orbit. Newton concluded that the Moon was in orbit
because its forward motion was balanced by the
falling motion caused by the pull of Earth’s gravity.
The story goes that Isaac Newton was sitting under an apple
tree when this idea struck him—the same force that pulls
apples from apple trees keeps the Moon circling Earth. What
did Newton mean? [The Earth’s gravity makes an apple fall to the ground. The Earth’s gravity also keeps the Moon in
orbit around the Earth.]
Call on two to three students to explain. Then ask,
According to this chapter, what else does gravity hold together? [Gravity hold the planets in orbit around the Sun. It
also holds together all the stars in the galaxy.]
© 2015 Sally Ride Science
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GRAVITY: CHAPTER 3
Gravity in the Universe
Ask students to refer to the concept maps they made on their Chapter 3 handouts. Tell students that there are
many ways to map the same set of concepts. Have pairs of students share their concept maps and discuss the key
concepts in Chapter 3. Tell students they may refine their maps if they wish.
Then, as a class, generate a concept map of the big ideas in Chapter 3 on the board. Begin with a central circle
labeled Gravity in the Universe. Draw a second level of circles and invite students to suggest what should be written
in each circle. These should be the big ideas covered in the chapter, not the details about an idea.
Then draw the next level of circles, connecting one or two circles to each of the big-idea circles. Call on students for
suggestions of what to write in each circle. Encourage students to suggest ways to rearrange the contents of the
circles if they have compelling reasons for doing so.
© 2015 Sally Ride Science
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GRAVITY: THINKING LIKE A SCIENTIST
Calculate Weights on Different Bodies in Space
Read Thinking Like a Scientist (pages 24-25) and answer the questions
Ask students to read Thinking Like a Scientist. Give them the Thinking Like A Scientist
handout and have them use it to answer the questions on page 25. Have students work in
small groups to discuss the questions and come to agreement on the answers. Then ask
each group to present to the class—each group should go through one question and show
how they arrived at their answer.
Interpreting Data
Scientists know that a good way to compare weights is to use a table.
The one here shows numbers that you can use to multiply by and find
an object’s weight throughout our solar system.
Use the information in the table to answer these questions
ANSWER KEY
1. A spacecraft weighs 349 kilograms (770 pounds) on Earth. What
will it weigh on Mars? [The spacecraft would weigh 130 kg on
Mars. The gravitational factor of Mars compared to Earth is 0.38.
That means the spacecraft would weigh 0.38 x 349 kg = 130 kg
on Mars.]
2. What would the spacecraft weigh on Jupiter? [On Jupiter, the spacecraft would weigh
886 kg. Jupiter’s gravitational factor compared to Earth is 2.54. That means the
spacecraft would weigh 2.54 x 349 kg = 886 kg on Jupiter.]
3. The legs of the spacecraft are designed to support up to 544 kilograms (1,200 pounds).
Could it be used on Venus? Explain. [Yes, the legs of the spacecraft are strong enough
to support the spacecraft’s weight on Venus. For Venus, the gravitational factor
compared to Earth is 0.91. That means the spacecraft will weigh less on Venus than it
does on Earth (0.91 x 349 kg = 320 kg) so the spacecraft legs can support it.]
4. How might a landing craft be designed differently for Pluto than for Mars? Why might
scientists want to design it differently for Pluto? [Because the dwarf planet Pluto is
really small (Pluto’s mass is only 0.2 percent of Earth’s mass), Pluto’s gravitational factor compared to Earth is
0.06. That means a landing craft designed for Pluto would weigh less than one-sixth of what it would weigh on
Mars, so its legs would not have to be as sturdy or strong.]
© 2015 Sally Ride Science
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GRAVITY: HOW DO WE KNOW?
Meet astronomer Dara Norman
Read How Do We Know? (pages 26-29)
Give students the How Do We Know? handout for Gravity. Tell them they should read the
first two questions on the handout. Then they should read The Issue section of How Do
We Know? (page 26) and answer the questions about it. Have them complete the rest of
the sections (The Expert, page 27; In the Field, page 28; Technology, page 29) in the same
way. Then go over each question as a class. Call on two or three students to share their
answers to each question.
ANSWER KEY
1. How did the science writer help you understand the topic? [Sample answer: The
science writer explains the topic by comparing gravity to glue. That comparison makes
it easy to picture how gravity pulls materials together.]
2. How did the science writer capture your interest? [Sample answer: The science writer
explained that we can’t see most matter, since it doesn’t reflect light. So the question
of how we know the matter is there is interesting. The writer made this into a little
mystery and then had a strange explanation—gravity bends light.]
3. What sparked Dara Norman’s interest in space? [Dara Norman’s interest in space began when she was growing
up. She spent hours roaming around Chicago’s Museum of Science and Industry. Dara says that ever since third
grade, she wanted to be an astronaut.]
4. What are some of the tools that Dara uses in her work as an astronomer? [Dara began exploring space using
telescopes to study quasars (the bright centers of active galaxies). Then she began to use gravity, which bends
light and can brighten a quasar’s light, as a tool.]
5. Why does Dara use eyeglasses to explain gravitational lensing? Explain what she means. [The human eye bends
light to focus images on the light-sensitive back part of the eye called the retina. The transparent cornea covering
the eye bends incoming light rays, which then enter the inside of the eye through the opening called the pupil.
Behind the pupil, the transparent lens further bends the light to focus it on the retina. Some people’s eyes have
problems focusing light because their eyes do not bend light properly. Eyeglasses (or contact lenses) provide the
extra bending power needed to focus light on the retina, whose light-sensitive cells transmit signals through the
optic nerve to the visual center inside the brain for processing. So Dara’s eyeglasses analogy is a good one! By
first explaining how eyeglasses help to bend light and focus it, she can more easily explain how gravity bends light
from distant galaxies.]
© 2015 Sally Ride Science
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GRAVITY: MATH CONNECTION
Weigh Different!
Answer the Math Connection questions
Give students the Math Connection handout and have them use it to answer the Math
Connection questions on page 29 of Gravity. Students should show their work for each
calculation.
Weigh Different!
How do you measure the gravitational pull between Earth and
you? Step on a scale! Scales measure weight—the force of
attraction between you and Earth. The amount of attraction
depends on the mass of each object and how far apart they
are. Find out how much you weigh on some other bodies in
the Universe. Do the math.
ANSWER KEY
Your weight is a measure of the force of Earth’s gravitational
attraction for you. Different celestial bodies have different gravitational pulls. Say you
weighed 45.5 kilograms (100 pounds) on Earth. You would weigh 1,274 kg (2,800) pounds
on the Sun. That’s because the gravitational pull of the Sun is 28 times that of Earth. Here
are all of the calculations for someone who weighs 45.5 kg (100 pounds):
My weight on the Sun: [1,274 kilograms = 28 × 45.5 kilograms; 2,800 pounds = 28 ×
100 pounds]
My weight on the Moon: [7.6 kilograms = 1/6 × 45.5 kilograms; 16.7 pounds = 1/6 ×
100 pounds]
My weight on Mars: [15 kilograms = 1/3 × 45.5 kilograms; 33.3 pounds = 1/3 × 100
pounds]
My weight on a white dwarf star: [59,150,000 kilograms = 1,300,000 × 45.5 kilograms; 130,000,000 = 1,300,000
× 100 pounds]
My weight on a neutron star: [6,370,000,000 kilograms = 140,000,000,000 × 45.5 kilograms;
14,000,000,000,000 pounds = 140,000,000,000 × 100 pounds]
© 2015 Sally Ride Science
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GRAVITY
Write a Science Article
The Hubble Space Telescope
Give students the Write a Science Article handout. It tells students to imagine they are
reporters for a kids’ science magazine. They are assigned to do some research and then
write an article about the Hubble Space Telescope. Allow students to visit the Hubble
website to research the mission: http://hubblesite.org.
Students should:
> describe some of the Hubble’s discoveries.
> tell what image they would direct Hubble to take if they
were operating the telescope.
Remind students to:
> come up with a headline that identifies the topic.
> write a lead (beginning) that grabs readers’ interest and
makes them want to keep reading.
> include facts that are interesting, odd, or funny.
> write a conclusion that connects the big ideas.
SCIENCE BACKGROUND
The Hubble Space Telescope is a space-based
telescope that was carried into orbit aboard the
space shuttle Discovery in 1990. From its position
above Earth’s atmosphere, Hubble has expanded
our understanding of the Universe—of star birth,
star death, galaxy evolution, and black holes in
particular. The telescope’s science instruments are
astronomers’ eyes on the universe. When Hubble
was first launched, its primary mirror had a minor
flaw that made it difficult for the telescope to
resolve faint objects. The mirror had been ground
to the wrong shape—it was too flat at the edges
by about 2 micrometers (0.00008 inches). This flaw
resulted in images that were not quite as sharp
as they could be. The telescope is in low Earth
orbit, so astronauts were able to correct the defect
during a space shuttle mission.
© 2015 Sally Ride Science
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GRAVITY: HEY, I KNOW THAT!
Study Guide
Complete the Hey, I Know That! study guide (page 30)
Have students use the Hey, I Know That! handout to answer the questions on page 30 of
Gravity. Have pairs of students discuss their answers. Ask several students to read their
answers aloud, and encourage others in the class to comment and expand on the answers.
ANSWER KEY
1. What two things affect the strength of gravity between two objects? (pages 8-9) [The
strength of gravity depends on the masses of the objects and the distance between
them. The larger the object, the stronger its gravity. And the closer the objects, the
stronger the gravitational pull between them.]
2. A softball player hits a high fly ball. On its way down, the softball falls 9.8 m/s for the
first second. What is its velocity after 5 seconds? (page 11) [After 5 seconds, the ball’s
velocity is 49 m/s. The ball’s velocity increases by 9.8 m/s every second that it falls. So
it falls at 9.8 m/s after 1 second, 19.6 m/s (9.8 m/s + 9.8 m/s) after 2 seconds, 29.4
m/s (9.8 m/s + 9.8 m/s + 9.8 m/s) after 3 seconds, 39.2 m/s (9.8 m/s +
9.8 m/s + 9.8 m/s + 9.8 m/s) after 4 seconds, and 49 m/s (9.8 m/s + 9.8
m/s + 9.8 m/s + 9.8 m/s + 9.8 m/s) after 5 seconds.]
3. Look at the photo of the astronaut on Earth and the Moon. Why is the
astronaut’s weight less on the Moon than on Earth? (pages 14-15) [The
Moon has less mass than Earth, so it has less gravity. That means the
Moon’s gravity pulls less on the astronaut.]
4. What is the mass of the astronaut on the Moon? (page 15) [The mass
of the astronaut on the Moon is 72.5 kilograms, the same as on Earth.
The astronaut’s weight changes when she goes from Earth to the Moon
because the Moon’s gravity is weaker. But her mass stays the same.
Mass is a measure of the amount of matter in an object; weight is a
measure of the pull of gravity on that matter.]
5. Draw a sketch to show how inertia and gravity combine
to keep the Moon or a spacecraft in orbit around Earth.
(pages 20-21) [The diagram on page 21, shown here,
gives an idea of what students’ sketches should look
like.]
© 2015 Sally Ride Science
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Key Concepts in Science
GRAVITY
STUDENT
HANDOUTS
© 2015 Sally Ride Science
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GRAVITY • Chapter 1
Gravity Basics: Notes for Chapter 1
As you read Chapter 1, write down the most important information you come across. Resist the urge to write down
everything that you read. Instead, focus on the big ideas, or gist, of what you are reading.
WHAT GOES UP . . .
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STRANGER THAN FICTION
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TUG-OF-WAR CHAMPION
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TO THE MOON AND BEYOND!
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© 2015 Sally Ride Science
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GRAVITY • Chapter 1
PICTURE THIS
Review your notes for Chapter 1. Create an illustrated summary of the key ideas in the chapter. Each important idea
should be represented by a drawing, a diagram, or other visual and should include a caption explaining the importance of
the image.
PUT IT ALL TOGETHER
Use your notes and illustrated summary to help you identify and list the most important ideas—the key concepts—in
Chapter 1.
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© 2015 Sally Ride Science
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GRAVITY • Chapter 2
Gravity on Earth: Notes for Chapter 2
As you read each section of Chapter 2, write down any questions that occur to you. Also write down any answers to your
questions that you find.
LOOK OUT BELOW!
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FASTER, FASTER!
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IT’S A TIE!
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YOU MUST RESIST
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A WEIGHTY TOPIC
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MASS STAYS THE SAME
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© 2015 Sally Ride Science
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GRAVITY • Chapter 2
PICTURE THIS
Review your notes for Chapter 2. Summarize the information about how falling objects accelerate by drawing a diagram
of a falling object. Use labels and a caption to explain your diagram.
PUT IT ALL TOGETHER
Use your notes and diagram to help you identify and list the most important ideas—the key concepts—in Chapter 2.
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© 2015 Sally Ride Science
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GRAVITY • Science Writing
Science Writing: How Gravity Affects a Sport
Choose a sport. Then answer the questions about how gravity and air resistance affect the sport.
1. How does gravity affect the motion of players or equipment, such as a ball, when the sport is being played? How
would this change if Earth’s gravity were weaker or stronger?
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2. How does air resistance affect the motion of the players or equipment? Do you think this is a significant effect? Why
or why not?
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3. Suppose a player learns about the effects of gravity and air resistance. Describe a way that the player’s performance
could be improved by applying this knowledge to the game.
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© 2015 Sally Ride Science
GRAVITY • Chapter 3
Gravity in the Universe: Notes for Chapter 3
As you read Chapter 3, write down the most important information you come across. Resist the urge to write down
everything that you read. Instead, focus on the big ideas, or gist, of what you are reading.
KEEPING IT TOGETHER
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BUILDING WITH GRAVITY
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CAUTION! CONSTRUCTION AHEAD
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WELCOME TO THE NEIGHBORHOOD
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“NOW PITCHING . . .”
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ROUND AND ROUND
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IN A GALAXY FAR, FAR AWAY . . .
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A POWERFUL FORCE
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© 2015 Sally Ride Science
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GRAVITY • Chapter 3
PICTURE THIS
Review your notes for Chapter 3. Summarize your notes by developing a concept map that makes sense to you. You might
start with a central circle labeled Gravity in the Universe. Extending from this circle might be other circles describing the
effect of gravity on our solar system, galaxies, and black holes.
PUT IT ALL TOGETHER
Use your notes and concept map to help you identify and list the most important ideas—the key concepts—in Chapter 3.
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© 2015 Sally Ride Science
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GRAVITY • Thinking Like a Scientist
Thinking Like a Scientist:
Calculate Weights on Different Bodies in Space
Read Thinking Like a Scientist on pages 24 and 25 of Gravity. Then
answer the questions.
Interpreting Data
Scientists know that a good way to compare weights is to use a table.
The one here shows numbers that you can use to multiply by and find an
object’s weight throughout our solar system.
Use the information in the table to answer the questions. Be sure to
show your calculations.
1. A spacecraft weighs 349 kilograms (770 pounds) on Earth. What will it weigh on Mars?
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2. What would the spacecraft weigh on Jupiter?
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3. The legs of the spacecraft are designed to support up to 544 kilograms (1,200 pounds). Could it be used on
Venus? Explain.
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4. How might a landing craft be designed differently for Pluto than for Mars? Why might scientists want to design it
differently for Pluto?
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© 2015 Sally Ride Science
GRAVITY • How Do We Know?
How Do We Know?
Gravity’s Spotlight on the Universe
Review the questions below for each section of How Do We Know? Then
read each section in the book and answer the questions.
THE ISSUE
1. How did the science writer help you understand the topic?
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2. How did the science writer capture your interest?
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THE EXPERT
3. What sparked Dara Norman’s interest in space?
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IN THE FIELD
4. What are some of the tools that Dara uses in her work as an astronomer?
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TECHNOLOGY
5. Why does Dara use eyeglasses to explain gravitational lensing? Explain what she means.
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© 2015 Sally Ride Science
GRAVITY • Math Connection
Math Connection: Weigh Different!
How do you measure the gravitational pull between Earth and
you? Step on a scale! Scales measure weight—the force of
attraction between you and Earth. The amount of attraction
depends on the mass of each object and how far apart they
are. Find out how much you weigh on some other bodies in the
Universe. Do the math.
Calculate your weight, in pounds and kilograms, on each
body. Show your calculations.
My weight on Earth: _________________ pounds _____________ kilograms
My weight on the Sun: ________________________________________________________________________
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My weight on the Moon: ______________________________________________________________________
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My weight on Mars: __________________________________________________________________________
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My weight on a white dwarf star: _______________________________________________________________
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My weight on a neutron star: ___________________________________________________________________
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© 2015 Sally Ride Science
GRAVITY • Write a Science Article
Write a Science Article: The Hubble Space Telescope
Imagine you are a reporter for a kids’ science magazine. You are assigned to write an article about the Hubble Space
Telescope. Follow your teacher’s instructions for researching the telescope. Then use this sheet to write an article that
describes some of the Hubble’s discoveries. Your article also should tell what image you would direct Hubble to take if
you were operating the telescope.
Be sure to:
> come up with a headline that identifies the topic.
> write a lead (beginning) that grabs readers’ interest and makes them want to
keep reading.
> include facts that are interesting, odd, or funny.
> write a conclusion that connects the big ideas.
Headline: _____________________________________________
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Caption:
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© 2015 Sally Ride Science
GRAVITY • Hey, I Know That!
Hey, I Know That! Study Guide
Use this sheet to answer the Hey, I Know That! questions on page 30 of Gravity.
1. What two things affect the strength of gravity between two objects? (pages 8-9)
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2. A softball player hits a high fly ball. On its way down, the softball falls 9.8 m/s for the first second. What is its velocity
after 5 seconds? (page 11)
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3. Look at the photo of the astronaut on Earth and the Moon. Why is
the astronaut’s weight less on the Moon than on Earth?
(pages 14-15)
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4. What is the mass of the astronaut on the Moon? (page 15)
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© 2015 Sally Ride Science
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GRAVITY • Hey, I Know That!
5. Draw a sketch to show how inertia and gravity combine to keep the Moon or a spacecraft in orbit around Earth.
(pages 20-21)
© 2015 Sally Ride Science
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