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  • Subject: Space Science
  • |
  • Grade(s): 6-8
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  • Duration: One class period

Lesson Plan Sections


Students will understand the following:
1. A digital radio message has been electronically transmitted into space by the Arecibo radio dish in Puerto Rico.
2. The purpose of the message is to alert any intelligent life in space to the existence of intelligent life on Earth.
3. In order for such a message to be effective, it must show that the senders (humans from Earth) are capable of advanced thinking, but it must not depend on the ability of extraterrestrials to understand any Earth language.


No materials are necessary for this activity. However, a computer with Internet access may be helpful to those students who wish to do optional research.


1. Initiate a class discussion by asking your students if they think there might be intelligent life in space. As your students express their opinions, ask them to back them up with scientific facts or logical reasoning.
2. Tell the class that some scientists believe that extraterrestrial advanced civilizations do exist. Ask students to brainstorm ideas for how we might find and get in touch with other intelligent life in space. Students should understand that because they cannot depend upon any Earth language, they should turn to other forms of communication, such as art, music, or mathematical symbols.
3. When students have shared their ideas, inform them that a digital radio message has already been electronically transmitted into space by the Arecibo radio dish in Puerto Rico.
4. Show them the message transmitted by the Arecibo radio dish, and ask them if they can figure out its significance:
x x x x x x   x x   X X X X
  x x x x           X X X X
      x x
      x x
(Write the message on the chalkboard, using squares instead of Xs. Use a larger square for the two rows of larger Xs at the right.)
5. When students have made several guesses about the meaning of the message, explain that it is a diagram of the solar system. The sun is on the right, and the smaller squares represent the nine planets in order. The number of squares in each column represents the relative sizes of the planets, and Earth is given special distinction by being raised above the others.
6. Ask students if they think an alien civilization would be able to decipher the message. Why, or why not? Do students think that even if intelligent aliens could not discover the actual meaning of the message, the message would at least succeed in communicating that it was sent by intelligent beings?
7. Invite students to suppose that they are in charge of extraterrestrial greetings. Divide the class into groups, and ask them to brainstorm ideas about the information or message they would include in an extraterrestrial greeting. How would they translate their greetings into terms appropriate for extraterrestrials?
8. Have each group present its completed message to the class and ask the rest of the class to attempt to decode it.
9. Encourage interested students to do further research on sending greetings into space and preparing to receive greetings from extraterrestrials.

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Encourage older students to tap their most advanced scientific and mathematical knowledge to create their messages.

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Discussion Questions

1. Discuss the meaning behind the statement "absence of evidence is not evidence of absence" as it relates to the search for extraterrestrial life. Why has this become a slogan of the SETI program? Why do you suppose Congress does not share SETI's enthusiasm?
2. Explain why there are so many false alarms for the SETI project. How can radio astronomers tell the difference between interference from human-made sources and authentic signals? Do you think scientists will have a difficult time convincing people if they ever get a true extraterrestrial signal?
3. If scientists ever determine for certain that intelligent life exists on other planets, it will probably have a tremendous effect on society. How would we be changed by such an earth-shattering discovery? What developments might we expect to see in the areas of religion, culture, and politics in particular?
4. Imagine that you have discovered three new planets—one with no atmosphere, one that is entirely covered by mountains of salt, and one that is orbiting extremely close to its star. How might life-forms on these imaginary planets have adapted over time to deal with such extreme conditions? What unfamiliar features might they have?
5. In the late 1960s, NASA constructed an expensive facility called the Lunar Receiving Lab (LRL) to quarantine and process samples brought by astronauts returning from the moon. While some scientists and members of Congress did not agree that the lab was necessary, others felt they needed to be exceedingly cautious to avoid contaminating Earth's biosphere with "moon microbes." The LRL was a sprawling complex that housed sterile vacuum chambers, an underground radiation bunker, and animals and plants to be exposed to the samples. Astronauts returning from the moon were required to remain in quarantine there for three weeks. Based on what you know about conditions on the moon, do you think the LRL's strict quarantine was a necessary precaution? Defend your answer.
6. Science fiction writers use extraterrestrials in stories not only to tap into readers' primal fears, but also as mirrors of ourselves—encouraging us to face difficult social, political, and environmental issues. For example, in the story "Before Eden" by Sir Arthur C. Clarke, the first plants discovered on another planet are accidentally destroyed by a bag of waste left behind by human explorers. The story subtly encourages readers to think about the effects of our environmental excesses. Think about the images of aliens you have seen in movies and television or read about in books. What "messages" did those movies, television shows, or books contain? Do you think it's useful for a writer to use images of aliens to send messages to humans? Why or why not?

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Accept all messages submitted by groups that worked cooperatively.

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First Contact
Have students write about Earth's first contact with an extraterrestrial life-form in the future. Each student should choose one of the following genres: science fiction, journalism, technical writing (rules for how to handle a "first contact"), or journal writing. Suggest that students' writing might include the public's initial reaction to the event, the details of the experience from a firsthand point of view, and ways in which life on Earth would change after the contact. After students have completed their writing, have them revise, and share or publish their work.

Radio Telescopes of the World
In order to receive messages that might be sent to Earth by an extraterrestrial advanced civilization, one radio telescope is good, but two or more working together are even better. Explain to students that interferometry is a process by which an array of two or more radio telescopes can work together to pick up weak signals. Divide your students into teams. Each team's goal is to plot the locations of two telescopes on a map of the world (use stickers on inflatable globes if possible), and then decide on the best location for a third radio telescope to add to the array. The initial telescopes are in Arecibo, Puerto Rico, at 18? 20' 36.6" N (latitude), 66? 45' 11.1" W (longitude); and Greenbank, West Virginia, at 38? 25' 58.7" N (latitude), 79? 50' 24.2" W (longitude).
Teams should keep in mind the following points when considering the best location for the third telescope:
  • The array of three telescopes should form a triangle.
  • All three telescopes should be spaced well apart because they can reveal more detail that way. Note: The distance between Arecibo and Greenbank is 1,593 miles (2,563 kilometers).
  • Weather conditions should be favorable for construction and maintenance of the new telescope. Too much rain, wind, or hail can cause damage to the dish. The team should also avoid areas prone to floods, earthquakes, tornadoes, and hurricanes.
  • The location for the new telescope should be as free as possible from radio interference, as should the area within the triangle formed by the three telescopes. Teams should consider population levels to determine which areas might be suitable.
Each team should present its chosen location to the class and explain what makes it a good choice.

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Suggested Readings

Searching for Alien Life: Is Anyone Out There?
Dennis Brindell Fradin, Twenty-First Century Books, 1997
From earliest times, people have wondered whether there is life in outer space. Read this entertaining and informative book about extraterrestrials and UFOs and decide for yourself whether they exist.

Special Effects in Film and Television
Jake Hamilton. DK Publishing, Inc., 1998.
Fabulous graphics and illustrations help us understand how special effects are created. Check out the step-by-step directions on how to create an alien. Do you want to use your imagination and try to create one?

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Who's Out There: Searching for Extraterrestrial Intelligence
SETI (Search for Extraterrestrial Intelligence) invites you to become a virtual astrobiologist and do simulated research for life in the Universe in this interactive online game.

Life on the Edge
It's a hands-on experiment designed for students of all ages to investigate life in extreme environments here on Earth, and to learn about the possibilities for life in extreme environments elsewhere in the Solar System.

SETI: The Drake Equation
The Drake Equation is a way to focus on the factors that determine how many intelligent, communicating civilizations there are in our Milky Way galaxy. Inputing your own assumptions into this online calculator yields the statistical probability for life in the galaxy.

NASA Astrobiologist Lynn Harper
Astrobiologist Lynn Harper answers student questions about the search for life in the Universe at Discovery Channel School Online's archived discussion webpage. Fascinating information from this expert is found by clicking on her name.

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

speaker    exobiologist
Definition: A scientist who studies evidence of life in space.
Context: When the exobiologists looked at the camera on Surveyor 3, there were streptococcus bacteria inside it.

speaker    optical fiber
Definition: A thin cable that transmits pulses of light.
Context: Operations at the radio telescope can be brought to a standstill by a dirty optical fiber.

speaker    radio astronomer
Definition: A specialist in the branch of astronomy that deals with radio waves transmitted from outside of the Earth's atmosphere.
Context: Radio astronomers use dish antennas to study the universe. They pick up natural radio waves emitted by everything from galaxies to stars to single hydrogen atoms floating in space.

speaker    sentient
Definition: Capable of sensation and at least rudimentary consciousness; consciously perceiving.
Context: Just knowing that somewhere else physics and chemistry put together another sentient creature with the ability to build radio telescopes is a big enough payoff for Jill Tarter.

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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: 6-8, 9-12
Subject area: space science
Understands essential ideas about the composition and structure of the universe and the Earth's place in it.
Benchmark 6-8:
Knows that although the planet Earth and our solar system appear to be somewhat unique, similar systems might yet be discovered in the universe.

Benchmark 6-8:
Knows that many billions of galaxies exist in the universe (each containing many billions of stars), and that nearly incomprehensible distances separate these galaxies and stars from one another and from Earth.

Benchmark 9-12:
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: 6-8
Subject area: life science
Knows about the diversity and unity that characterize life.
Is aware of evidence that supports the idea of unity among organisms despite the fact that some species look very different from one another (e.g., similarity of internal structures in different organisms, similarity of chemical processes in different organisms, evidence of common ancestry).

Grade level: 9-12
Subject area: physical science
Understands motion and the principles that explain it.
Knows the range of the electromagnetic spectrum (e.g., radio waves, microwaves, infrared radiation, visible light, ultraviolet radiation, x-rays, gamma rays); knows that electromagnetic waves result when a charged object is accelerated or decelerated, and that the energy of electromagnetic waves is carried in packets whose magnitude is inversely proportional to wavelength.

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 and the observer; if either the source or the observer is moving toward the other, the observed wavelength is shorter; if either is moving away, the wavelength is longer.

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Summer Productions, Inc.

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