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6-8 > Astronomy/Space
Grade level: 6-8 Subject: Astronomy/Space Duration: Two class periods
Objectives | Materials | Procedures | Adaptations | Discussion Questions | Evaluation | Extensions | Suggested Readings | Links | Vocabulary | Academic Standards | Credit
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Students will understand the following:
1. Even though black holes all have characteristics in common, they come in three different sizes.
2. Each size black hole has characteristics different from the others.

Only research materials are required for this activity. You might want to have a selection of sources on hand in the classroom, but students should go to the library or the Internet for additional research.
Reference materials on black holes
A computer with Internet access

1. Review with your students what they have learned about black holes.
2. Make sure they understand that, while black holes have characteristics in common, they differ with regard to size. Explain that black holes come in three sizes: stellar mass black holes, supermassive black holes, and mini-black holes. Explain further that particular characteristics are associated with each size.
3. Divide the class into three teams, and assign each team to research one of the black-hole types discussed above.
4. Tell students that each team will prepare a presentation based on its research, which should include the following:
  1. characteristics of the type of black hole
  2. lifetime of the type of black hole
  3. locations (or suspected locations) of the type of black hole
  4. evidence for existence of the type of black hole
5. Tell students to keep track of the sources for their facts so that they or other interested classmates can go back to those sources for further information.
6. Encourage students to include visuals in their reports.
7. After each team has presented its report, invite students to participate in creating on the chalkboard a compare-and-contrast chart showing the similarities and differences among the three types of black holes.
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Adaptations for Older Students:
Have each team member submit a detailed written report on one of the four items included in the team’s report: characteristics, lifetime, locations, evidence of existence.
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Discussion Questions

1. Discuss how Newton’s view of gravity differs from Einstein’s view of gravity.
2. Describe how a black hole is formed from the time a massive star begins its collapse.
3. Knowing that density is defined as mass per unit volume, discuss the mathematical characteristics of a singularity (values of mass, density, volume, and radius).
4. Describe the steps involved in determining the mass of a black hole. What do you have to measure or observe in order to estimate the mass?
5. If you were observing a probe entering the event horizon of a black hole, you would see it “hovering for an eternity and destroyed in an instant.” Discuss the meaning of this phrase as it applies to conditions near a black hole.
6. Discuss the objective of the Gravity Probe B satellite and its relevance to the study of gravity.
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You can evaluate each group’s written product using the following three-point rubric:
  • Three points:report well-researched, information clearly and logically organized, presentation interesting and lively
  • Two points:report adequately researched, information sufficiently organized, presentation dull
  • One point:report insufficiently researched, information inadequately organized, presentation poorly prepared
You can ask your students to contribute to the assessment rubric by determining a minimum number of facts to be presented in a report and setting up criteria for an interesting and lively presentation.
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Fantastic Tales
Have students discuss the paradoxes associated with black holes and speculate on the possibility of using black holes for time travel. Following the discussion, have students choose from the following activities:
1. Collect several examples of short stories based on black holes. Compare the stories with regard to scientific accuracy and the function of black holes in the plots. In each case, describe how the author portrays the relationship between the characters and the black hole. Is the black hole treated like a character, event, place, or all three?
2. Write an original short story, narrative, poem, song, or news article about space travel near, through, or inside a black hole. Focus on the reactions and experiences of each of the characters as they come face to face with the abyss.
3. Collect examples of references to black holes in music and television. Describe how black holes are used in these works and what reactions they elicit. When have black holes been used as the focus of comedy or as a metaphor for something else (like helplessness or greed)?

Breaking Free
Astronomers use the termescape velocityto refer to the minimum speed necessary to break free from the pull of gravity of a planet, moon, star, or black hole and not be pulled back. To appreciate the limits imposed by mass, have students research and compare the escape velocities for objects on the moon, Earth, Jupiter, the sun, Rigel, a white dwarf, a neutron star, and a black hole. With these comparisons in mind, have the class debate future plans for space exploration.

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Suggested Readings

Mysteries of Deep Space: Black Holes, Pulsars, and Quasars
Isaac Asimov. Gareth Stevens Publ., 1994.
Read about the birth of the sun and other stars, celestial energy, black holes, and quasars. Can you imagine something that spins 33 times a second or is 12 billion light years away? This book helps you understand these concepts and phenomena.

Prisons of Light: Black Holes
Kitty Ferguson. Cambridge University Press, 1996.
What is a black hole? Could we survive a visit? What do black holes teach us about the universe? This comprehensive, detailed, yet easy-to-read book answers questions about these unseen phenomena whose existence has been proven through physics and mathematics.

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Black Hole Movies Online
A collection of computer-generated movies that portray different aspects of black holes. Travel to the event horizon but be careful not to fall in!

Newton's Law of Universal Gravitation:
No matter how you look at it, from Newton to Einstein, gravity is responsible for the creation of black holes. Newton’s Universal Law of Gravity will give you a start for a later understanding Einstein’s General theory of Relativity.

Black Holes - Portals Into The Unknown
High school students showcase their work on “Black Holes” in this 1997 THINK QUEST entry rich with links relating to black holes. Encourage your budding webpage designers to submit their creations to the next THINK QUEST competition.

Rush’s “Cygnus X-1”
The mysterious signals coming from Cygnus X-1 led astronomers to believe they were “looking” at the first real candidate for a black hole. Read the story —do you think they were right?

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Click on any of the vocabulary words below to hear them pronounced and used in a sentence.

speaker    black hole
Definition:An object with a gravitational field so strong that light cannot escape from it. It is believed to be created in the collapse of a very massive star.
Context:Everybody has heard of black holes; no one has really seen them.

speaker    gravity
Definition:A fundamental physical force that is responsible for interactions that occur because of mass. The force of gravity from an object is inversely proportional to the square of the distance away from the object.
Context:Newton reasoned that all matter in the universe has gravity.

speaker    mass
Definition:A measure of the amount of material an object contains, which causes it to have weight in a gravitational field.
Context:The more mass a body has, the more gravity.

speaker    supernova
Definition:The explosion of a very large star in which the star may reach a maximum intrinsic luminosity one billion times that of the sun.
Context:When a giant star switches off, it goes out with a bang. While we see the outward explosion as a supernova, this masks the implosion going on inside.

speaker    space-time
Definition:A system of one temporal (time) and three spatial coordinates by which any physical object or event can be located. Also called the space-time continuum.
Context:Space and time seem to be woven together to form the flexible four-dimensional fabric of the universe: so-called space-time.

speaker    singularity
Definition:A point or region of infinite mass density at which space and time are infinitely distorted by gravitational forces and which is thought to be the final state of matter in a black hole.
Context:The most terrifying concept of astrophysics lurks at the bottom of a black hole—the singularity—where nothing, not even light, can escape.

speaker    radio galaxy
Definition:A galaxy that is a powerful source of radio waves.
Context:Mighty jets of energized particles are blasted into space from invisible engines at the hearts of these so-called radio galaxies–further evidence that a black hole is driving the process.

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This lesson plan may be used to address the academic standards listed below. These standards are drawn from Content Knowledge: A Compendium of Standards and Benchmarks for K-12 Education: 2nd Edition and have been provided courtesy of theMid-continent Research for Education and Learningin Aurora, Colorado.
Grade level:9-12
Subject area:space science
Understands essential ideas about the composition and structure of the universe and the Earth’s place in it.
Knows the ongoing processes involved in star formation and destruction (e.g., stars condense by gravity out of clouds of molecules of the lightest elements; nuclear fusion of light elements into heavier ones occurs in the stars’ extremely hot, dense cores, releasing great amounts of energy; some stars eventually explode, producing clouds of material from which new stars and planets condense).

Knows common characteristics of stars in the universe (e.g., types of stars include red and blue giants, white dwarfs, neutron stars, and black holes; stars differ in size, temperature, and age, but they all appear to be made up of the same elements and to behave according to the same principles; most stars exist in systems of two or more stars orbiting around a common point).

Knows ways in which technology has increased our understanding of the universe (e.g., visual, radio, and x-ray telescopes collect information about the universe from electromagnetic waves; computers interpret vast amounts of data from space; space probes gather information from distant parts of the solar system; accelerators allow us to simulate conditions in the stars and in the early history of the universe).

Grade level:9-12
Subject area:physical science
Understands energy types, sources, and conversions, and their relationship to heat and temperature.
Knows that nuclear reactions convert a fraction of the mass of interacting particles into energy (fission involves the splitting of a large nucleus into smaller pieces; fusion is the joining of two nuclei at extremely high temperature and pressure) and release much greater amounts of energy than atomic interactions.

Grade level:9-12
Subject area:physical science
Understands basic concepts about the structure and properties of matter.
Knows that matter is made up of tiny particles called atoms, and different arrangements of atoms into groups compose all substances.

Grade level:9-12
Subject area:physical science
Understands motion and the principles that explain it.
Knows that apparent changes in wavelength can provide information about changes in motion because the observed wavelength of a wave depends upon the relative motion of the source of the observer; if either the source or observer is moving toward the other, the observed wavelength is shorter; if either is moving away, the wavelength is longer.

Understands general concepts related to the theory of special relativity (e.g., in contrast to other moving things, the speed of light is the same for all observers, no matter how they or the light source happen to be moving; nothing can travel faster than the speed of light).

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Lee Ann Hennig, an astronomy teacher at Thomas Jefferson High School for Science and Technology in Alexandria, Virginia.
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